bluuebunny/crossref_metadata_2025 huggingface dataset:
Thinking Through Networks and Their Spatiality: A Critique of the US (Public) War on Terrorism and its Geographic Discourse
Authors: Ettlinger Nancy , Bosco Fernando
Published: April 2004

Conventional thinking about war is encumbered by an inappropriate geographic paradigm that conceptualizes “targets” in terms of fixed latitudinal/longitudinal locations. This paper reconceptualizes terms such as “war” and “targets” to recognize intangible problems and develop appropriate counter‐terrorist strategies. This requires geographic inquiry focused on spatiality, not on location. We frame our discussion about terrorist networks (Al‐Qaeda in particular) in terms of understanding a network's sense of place and sense of space. The former “places” a network's meeting and recruiting grounds; the latter clarifies the operational dynamics of a network across space, at different scales, from the body to the neighborhood, to the region, and across nations. We argue that the roots of terrorism lie in conditions of disenfranchisement in particular types of places, understanding, however, that the socio‐cultural fabric of a terrorist network such as Al‐Qaeda evolves across space as well as time. Counter‐terrorist strategies should target neither people nor places but rather the conditions that give rise to terrorism; further, “intelligence” should focus on network dynamics, beyond particular people in particular places. We draw from network theories (specifically actor network theory and network approaches in economic sociology) to unravel network dynamics, and we draw from the literature on spatiality to interpret such dynamics in space, over time. We advocate a non‐military engagement with terrorism on both moral and strategic grounds; here we focus on the strategic dimension, the value of which has received scant attention.
Functional responses of plants to elevated atmospheric CO2– do photosynthetic and productivity data from FACE experiments support early predictions?
Authors: Nowak Robert S. , Ellsworth David S. , Smith Stanley D.
Published: April 2004

Results from 16 free‐air CO2 enrichment (FACE) sites representing four different global vegetation types indicate that only some early predictions of the effects of increasing CO2 concentration (elevated [CO2]) on plant and ecosystem processes are well supported. Predictions for leaf CO2 assimilation (Anet) generally fit our understanding of limitations to photosynthesis, and the FACE experiments indicate concurrent enhancement of photosynthesis and of partial downregulation. In addition, most herbaceous species had reduced leaf nitrogen (N)‐content under elevated [CO2] and thus only a modest enhancement of Anet, whereas most woody species had little change in leaf N with elevated [CO2] but a larger enhancement of Anet. Early predictions for primary production are more mixed. Predictions that enhancement of productivity would be greater in drier ecosystems or in drier years has only limited support. Furthermore, differences in productivity enhancements among six plant functional types were not significant. By contrast, increases in productivity enhancements with increased N availability are well supported by the FACE results. Thus, neither a resource‐based conceptual model nor a plant functional type conceptual model is exclusively supported by FACE results, but rather both species identity and resource availability are important factors influencing the response of ecosystems to elevated [CO2].

Contents

Summary
1

I.
Introduction
2

II.
Early assessments of [CO2] responses in natural ecosystems
2

III.
Global network of FACE sites
4

IV.
Assimilation and leaf N‐content
5

V.
Primary productivity
13

VI.
Response of plant functional types
20

VII.
Conclusions
23

Acknowledgements
24

References
24
Gastric tonometry and monitoring gastrointestinal perfusion: using research to support nursing practice
Authors: Marshall Andrea P , West Sandra H
Published: April 2004

• The principles and physiological underpinnings of gastric tonometry are reviewed

• Tonometric variables, including the PtCO2, pHi and CO2gap, are described and critiqued as measurements of gastrointestinal perfusion

• Increases in gastrointestinal CO2unrelated to gastrointestinal hypoperfusion are discussed within different clinical contexts

• The technical limitations of gastric tonometry, including procedural errors and PtCO2measurement are discussed in relation to the accuracy of tonometric measurements

• Tonometric measurement using semi‐continuous air tonometry is introduced as a strategy to minimize technical limitations
Simple and Efficient Recognition of Migraine With 3‐Question Headache Screen
Authors: Cady Roger K. , Borchert Leona D. , Spalding William , Hart Carolyn C. , Sheftell Fred D.
Published: April 2004

Objective.—To correlate the results of a new 3‐question headache screen to 3 established methods of diagnosing migraine: the International Headache Society diagnostic criteria, physician's clinical impression, and presence of recurring disabling headaches.

Background.—A simple tool to recognize patients who experience migraine may facilitate diagnosis of this debilitating and frequently undiagnosed condition.

Methods.—Primary care physicians and neurologists in the United States enrolled 3014 adults with a diagnosis of migraine based on one of the following: International Headache Society criteria, an investigator's clinical impression, or presence of recurring disabling headaches. Each patient completed a 3‐question headache screen: (1) Do you have recurrent headaches that interfere with work, family, or social functions? (2) Do your headaches last at least 4 hours? (3) Have you had new or different headaches in the past 6 months? A diagnosis of migraine was suggested by a yes answer to questions 1 and 2 and a no answer to question 3.

Results.—The 3‐question headache screen identified migraine in 77% of the study population; including 78% of the patients enrolled based on International Headache Society criteria, 74% based on clinical impression, and 68% because of recurring disabling headaches.

Conclusions.—Positive 3‐question headache screen results agreed well with migraine diagnoses based on International Headache Society criteria, clinical impressions, and presence of recurring disabling headaches. These findings support use of the 3‐question headache screen to recognize migraine.
Correlation between ST Elevation and Q Waves on the Predischarge Electrocardiogram and the Extent and Location of MIBI Perfusion Defects in Anterior Myocardial Infarction
Authors: Zafrir Barak , Zafrir Nili , Gal Tuvia Ben , Adler Yehuda , Iakobishvili Zaza , Rahman M. Atiar , Birnbaum Yochai
Published: April 2004

Background: The common electrocardiographic subclassification of anterior acute myocardial infarction (AMI) is not reliable in presenting the exact location of the infarct. We investigated the relationship between predischarge electrocardiographic patterns and the extent and location of perfusion defects in 55 patients with first anterior AMI.

Methods: Predischarge electrocardiogram was examined for residual ST elevations and Q waves which were correlated with technetium‐99m‐sestamibi function and perfusion scans.

Results: Patients with ST elevations in V2–V4 and Q waves in leads V3–V5 had worse global perfusion scores. Perfusion defects in the apex inferior segment were significantly less frequent in patients with Q waves in leads I and aVL (11% vs 54%, P = 0.027; and 22% vs 60%, P = 0.011, respectively). Patients with Q wave in aVF had more frequently involvement of the apex inferior segment (80% vs 40%; P = 0.035). Patients with Q wave in lead II had significantly more frequent perfusion defects in the inferior wall. ST elevation in V3 and V4 was associated with perfusion abnormalities of the infero‐septal segments. ST elevation in V5 and V6 and Q wave in V5 were associated with regional perfusion defects in apical inferior segment (73% vs 30%, P = 0.002), extending into the mid inferior segment (55% vs 18%, P = 0.005 for Q wave in V5). Q wave in lead aVL is associated with less apical and inferior involvement. Q waves in leads II and aVF are a sign of inferior extension of the infarction.

Conclusions: Residual ST elevation in leads V3 and V4 are more frequently associated with involvement of the apical‐inferoseptal segment rather than the anterior wall. Residual ST elevation and Q waves in V5 are related to a more inferior rather than a lateral involvement.
Effects and Significance of Premature Beats on Fractal Correlation Properties of R‐R Interval Dynamics
Authors: Peltola Mirja A. , Seppänen Tapio , Mäkikallio Timo H. , Huikuri Heikki V.
Published: April 2004

Background: Premature beats (PBs) have been considered as artifacts producing a bias in the traditional analysis of heart rate (HR) variability. We assessed the effects and significance of PBs on fractal scaling exponents in healthy subjects and patients with a recent myocardial infarction (AMI).

Methods: Artificial PBs were first generated into a time series of pure sinus beats in 20 healthy subjects and 20 post‐AMI patients. Thereafter, a case‐control approach was used to compare the prognostic significance of edited and nonedited fractal scaling exponents in a random elderly population and in a post‐AMI population. Detrended fluctuation analysis (DFA) was used to measure the short‐term (α1) and long‐term (α2) fractal scaling exponents.

Results: Artificial PBs caused a more pronounced reduction of α1 value among the post‐AMI patients than the healthy subjects, for example, if >0.25% of the beats were premature a >25% decrease in the α1 was observed in post‐AMI patients, but 4% of the premature beats were needed to cause a 25% reduction in α1 in healthy subjects. Both edited (1.01 ± 0.31 vs 1.19 ± 0.27, P < 0.01) and unedited α1 (0.71 ± 0.33 vs 0.89 ± 0.36, P < 0.05) differed between the patients who died (n = 42) and those who survived (n = 42) after an AMI. In the general population, only unedited α1 differed significantly between survivors and those who died (0.96 ± 0.19 vs 0.83 ± 0.27, P < 0.05).

Conclusions: Unedited premature beats result in an increase in the randomness of short‐term R‐R interval dynamics, particularly in post‐AMI patients. Premature beats must not necessarily be edited when fractal analysis is used for risk stratification.
Maximum P Wave Duration and P Wave Dispersion in Adult Patients with Secundum Atrial Septal Defect: The Impact of Surgical Repair
Authors: Guray Umit , Guray Yesim , Mecit Burcu , Yilmaz M. Birhan , Sasmaz Hatice , Korkmaz Sule
Published: April 2004

Background: Patients with atrial septal defect (ASD) have an increased risk for atrial fibrillation (AF). Previously it was shown that maximum P wave duration and P wave dispersion in 12‐lead surface electrocardiograms are significantly increased in individuals with a history of paroxysmal AF. We studied P maximum and P dispersion in adult patients with ASD during normal sinus rhythm. In addition, the impact of surgical closure of ASD on these variables within 1 year after surgery was evaluated.

Methods: Thirty‐four patients (21 women, 13 men; mean age: 35 ± 11 years) operated on for ostium secundum type ASD and 24 age‐matched healthy subjects (13 women, 11 men; mean age: 37 ± 10 years) were investigated. P maximum, P minimum, and P dispersion (maximum – minimum P wave duration) were measured from the 12‐lead surface electrocardiography.

Results: P maximum was found to be significantly longer in patients with ASD as compared to controls (115.2 ± 9 vs 99.3 ± 14 ms; P < 0.0001). In addition, P dispersion of the patients was significantly higher than controls (37 ± 9 vs 29.8 ± 10 ms; P = 0.003). P minimum was not different between the two groups (P = 0.074). After surgical repair of ASD, 10 patients (29%) experienced one or more episodes of paroxysmal AF. Patients with postoperative AF were older (45 ± 6 vs 30 ± 10 years; P = 0.001), and had a higher preoperative pulmonary artery peak systolic pressure as compared to those without postoperative AF (51 ± 11 vs 31 ± 9 mmHg; P < 0.0001). No significant difference in the pulmonary‐to‐systemic flow ratio was observed preoperatively between the two groups (P = 0.56). P maximum and P dispersion were significantly higher in patients with postoperative paroxysmal AF at baseline and at postoperative first month, sixth month, and first year as compared to those without it (for P maximum P = 0.027, P = 0.014, P = 0.001, P < 0.0001, respectively; for P dispersion P = 0.037, P = 0.026, P = 0.001, P < 0.0001, respectively). In addition, in patients with postoperative AF, no significant changes were detected in both of these P wave indices during postoperative follow‐up. However, in the other group, P maximum and P dispersion were found to be significantly decreased at postoperative 6 months and 1 year as compared to baseline. P minimum was similar throughout the postoperative follow‐up as compared to baseline in both groups.

Conclusions: Mechanical and electrical changes in atrial myocardium may cause greater P maximum and P dispersion in patients with ASD. Surgical closure of the ASD can regress these pathological changes of atrial myocardium with a result in decreased P maximum and P dispersion. However, higher P maximum and P dispersion at baseline, which have not decreased after surgery, may be associated with postoperative paroxysmal AF, especially for older patients.
A comparative study on the use of a HA/collagen/chondroitin sulphate biomaterial (Biostite®) and a bovine‐derived HA xenograft (Bio‐Oss®) in the treatment of deep intra‐osseous defects
Authors: Scabbia Alessandro , Trombelli Leonardo
Published: April 2004

Objectives: This parallel‐group, randomized, clinical trial was designed to evaluate the clinical outcome of deep intra‐osseous defects following reconstructive surgery with the use of a synthetic hydroxyapatite/equine Type I collagen/chondroitin sulphate biomaterial (Biostite®), as compared to a bovine‐derived hydroxyapatite xenograft (Bio‐Oss®).

Material and methods: Twenty‐four systemically healthy subjects with moderate to advanced periodontitis, 11 females and 13 males, aged 30–64 years, seven smokers, were selected. Patients presented with one interproximal deep intra‐osseous defect (intra‐osseous component4 mm) as clinically and radiographically evaluated. Immediately before surgery and 12 months after surgery, pocket probing depth (PPD), clinical attachment level (CAL) and radiographic depth of the defect (DEPTH) were evaluated.

Results: Thirteen defects were treated with Biostite® (test) and 11 defects with Bio‐Oss® (control). In the test group, PPD amounted to 7.8±1.3 mm before surgery, and decreased significantly to 3.6±1.6 mm 12 months following surgery, while in the control group PPD significantly decreased from 7.5±2.0 mm pre‐surgery to 3.1±1.0 mm post‐surgery. At 1 year, CAL gain and DEPTH gain were 2.9±1.9 and 2.5±1.4 mm, respectively, in the test group, and 4.0±2.4 mm and 3.1±1.8 mm, respectively, in the control group. No statistically significant differences for PPD reduction, CAL gain and DEPTH gain were detected between the groups.

Conclusions: The results of the present study indicate that both Biostite® and Bio‐Oss® grafting biomaterials have determined a clinically and statistically significant improvement in terms of CAL gain, PPD reduction and radiographic DEPTH gain when used for the treatment of deep intra‐osseous defects.
The association between neutrophil numbers and interleukin‐1α concentrations in gingival crevicular fluid of smokers and non‐smokers with periodontal disease
Authors: Petropoulos Georgios , McKay Ian J. , Hughes Francis J.
Published: April 2004

Objectives: To test whether neutrophil numbers are directly correlated with interleukin‐1α (IL‐1α) concentrations in gingival crevicular fluid (GCF) of patients with periodontitis, and to investigate the effects of smoking on these parameters.

Materials and Methods: A total of 99 GCF samples from 33 patients (14 smokers) suffering from severe chronic periodontitis were collected using Durapore™ filter strips. Polymorphonuclear leucocyte (PMN) numbers were counted using a Coulter cell counter and IL‐1α levels were determined by ELISA. Total GCF protein was measured by Bio‐Rad assay as a surrogate measure of GCF volume.

Results: Mean IL‐1α concentrations were significantly reduced in smokers compared with non‐smokers (non‐smokers: 3.29±2.02 pg/μg protein, smokers 1.59±1.13 pg/μg protein). There was no association between PMN numbers and IL‐1α concentrations found when analysed either by site or by patient. PMN numbers were not significantly different between the two groups (non‐smokers: 1.16 × 106±1.04 × 106; smokers: 7.30 × 105±8.07 × 105). Smoking did not affect mean total protein concentration of samples.

Conclusions: Smoking significantly decreased IL‐1α concentrations in GCF without affecting GCF volume sampled. The lack of association between IL‐1α concentration and neutrophil numbers suggests that the reduced IL‐1α concentrations seen in smokers is independent of any possible effect of smoking on neutrophil chemotaxis, and further suggests that smoking may directly inhibit IL‐1α production.
Interleukin‐4 gene polymorphisms in Japanese and Caucasian patients with aggressive periodontitis
Authors: Gonzales J. R. , Kobayashi T. , Michel J. , Mann M. , Yoshie H. , Meyle J.
Published: April 2004

Objectives: Recently, interleukin (IL) 4 gene polymorphisms have been analyzed in association with periodontitis. Genetic differences between Caucasian and Japanese patients with periodontitis have previously been detected. The aim of the present study was to analyze IL‐4 genotypes in Caucasian and Japanese patients with aggressive periodontitis (AgP).

Material and Methods: One hundred and twenty‐four subjects were included in the study, 31 Japanese and 30 Caucasian patients with generalized AgP, plus 30 Japanese and 33 Caucasian healthy controls. IL‐4 polymorphisms were determined by polymerase chain reaction. A logistic regression was used to investigate the possible association of the genotypes with the disease in both populations. Odds ratio (OR) estimates were analyzed for allele frequencies.

Results: No significant association of IL‐4 polymorphisms with the risk of AgP was determined in either population. However, the allele frequencies showed different results between populations. The carriage of the polymorphism in intron 2 was higher in Caucasian patients compared with controls (OR: 2.0, 95% confidence interval: [1.0;4.2]. Furthermore, the frequency of the IL‐4 promoter/intron 2 composite genotype (PP+/IP+) in patients and controls, respectively, was found to be approximately 25% and 60% higher in the Japanese population than in the Caucasian population.

Conclusion: There was no evidence of an association of IL‐4 genotypes and AgP in either population, although the frequencies of the IL‐4 genotypes in the Japanese and the Caucasians were different.
Periodontitis and atherogenesis: causal association or simple coincidence?
Authors: D'Aiuto Francesco , Parkar Mohammed , Andreou Georgios , Brett Peter M. , Ready Derren , Tonetti Maurizio S.
Published: April 2004

Objectives: The aim of this study was to assess the systemic effects of treating severe widespread periodontitis in a population of otherwise healthy individuals by examining treatment associated changes in markers of inflammation that are also implicated in cardiovascular atherosclerotic diseases. The potential impact of specific polymorphisms in cytokine genes known to influence both periodontitis and cardiovascular diseases was also examined.

Materials and Methods: A convenience sample of patients affected with severe generalised periodontitis was enrolled into a prospective single blind longitudinal intervention trial with a 6 months follow‐up. Serum C‐reactive protein (CRP) and interleukin‐6 (IL‐6) levels were assessed by high‐sensitivity assays. Serological and clinical periodontal parameters were evaluated at baseline, 2 and 6 months after completion of non‐surgical periodontal therapy.

Results: In the 94 subjects that completed this pilot trial improvements in all clinical periodontal parameters were achieved. These were accompanied with significant reductions in serum IL‐6 and CRP concentrations. In a multivariate model, serum CRP levels were significantly associated with the outcome of periodontal treatment after correcting for potential covariates (age, body mass index, gender, smoking) and polymorphisms in the IL‐6 (−174 C/G) and IL‐1A (−889) genes. A median decrease in serum CRP of 0.5 mg/l (95% CI 0.4–0.7 mg/l) was observed 6 months after completion of periodontal therapy in this population. Subjects with above average response to periodontal therapy (<30 residual pockets and <30% of sites bleeding on probing) accounted for the observed improvement in serum CRP.

Conclusions: Control of periodontitis, achieved with non‐surgical periodontal therapy, significantly decreased serum mediators and markers of acute phase response. The significance of the serum response was associated with the half of the population that responded better to non‐surgical periodontal therapy. The results of this pilot study indicate that severe generalised periodontitis causes systemic inflammation. This is consistent with a causative role of periodontitis in atherogenesis.
Oncotic pressures opposing filtration across non‐fenestrated rat microvessels
Authors: Adamson R. H. , Lenz J. F. , Zhang X. , Adamson G. N. , Weinbaum S. , Curry F. E.
Published: April 2004

We hypothesized that ultrafiltrate crossing the luminal endothelial glycocalyx through infrequent discontinuities (gaps) in the tight junction (TJ) strand of endothelial clefts reduces albumin diffusive flux from tissue into the ‘protected region’ of the cleft on the luminal side of the TJ. Thus, the effective oncotic pressure difference (σ□π) opposing filtration is greater than that measured between lumen and interstitial fluid. To test this we measured σ□π across rat mesenteric microvessels perfused with albumin (50 mg ml−1) with and without interstitial albumin at the same concentration within a few micrometres of the endothelium as demonstrated by confocal microscopy. We found σ□π was near 70% of luminal oncotic pressure when the tissue concentration equalled that in the lumen. We determined size and frequency of TJ strand gaps in endothelial clefts using serial section electron microscopy. We found nine gaps in the reconstructed clefts having mean spacing of 3.59 μm and mean length of 315 nm. The mean depth of the TJ strand near gaps was 67 nm and the mean cleft path length from lumen to interstitium was 411 nm. With these parameters our three‐dimensional hydrodynamic model confirmed that fluid velocity was high at gaps in the TJ strand so that even at relatively low hydraulic pressures the albumin concentration on the tissue side of the glycocalyx was significantly lower than in the interstitium. The results conform to the hypothesis that colloid osmotic forces opposing filtration across non‐fenestrated continuous capillaries are developed across the endothelial glycocalyx and that the oncotic pressure of interstitial fluid does not directly determine fluid balance across microvascular endothelium.
Vasodilatation is obligatory for contraction‐induced hyperaemia in canine skeletal muscle
Authors: Hamann Jason J. , Buckwalter John B. , Clifford Philip S.
Published: April 2004

There is a rapid increase in blood flow to active skeletal muscle with the onset of exercise, but the mechanism(s) eliciting this increase remains elusive. We hypothesized that the rapid increase in blood flow to active skeletal muscle with the onset of exercise is attributable to vasodilatation as a consequence of smooth muscle hyperpolarization. To test this hypothesis we examined the blood flow response to a brief tetanic contraction in which potassium (K+) was infused intra‐arterially to elevate the [K+]o and clamp the smooth muscle membrane potential within the skeletal muscle vascular bed. In six anaesthetized beagle dogs control contractions increased hindlimb blood flow by 97 ± 14 ml min−1. During K+ infusion the hyperaemic response to contraction was 8 ± 3 ml min−1. Since the hindlimb blood flow was reduced during K+ infusion, a similar reduction in baseline blood flow was produced with phenylephrine infusion. During phenylephrine infusion the hyperaemic response to contraction was preserved (89 ± 23 ml min−1). Recovery contractions performed after the discontinuation of the K+ infusion elicited blood flow responses similar to control (100 ± 11 ml min−1). In a separate experimental protocol using the isolated gastrocnemius muscle of mongrel dogs (n= 6) K+ infusion did not alter force production by the skeletal muscle. Our data indicate that in the absence of vasodilatation, there is virtually no change in blood flow. One implication of this finding is that the muscle pump cannot be responsible for the initial contraction‐induced hyperaemia. We conclude that the increase in blood flow immediately following a single muscle contraction is due to vasodilatation, presumably as a consequence of smooth muscle hyperpolarization.
Gravitational slingshot
Authors: Dykla John J. , Cacioppo Robert , Gangopadhyaya Asim
Published: April 2004

The slingshot effect is an intriguing phenomenon that has been used effectively by NASA to send spacecraft to outer edges of the solar system. This phenomenon can be satisfactorily explained by Newtonian physics. However, if it is presented as a problem involving four-momentum conservation, the methods of relativistic kinematics easily lead to the conditions necessary for an accelerating as well as a retarding scenario. This problem provides an example that showcases the frequent utility of relativistic methods to analyze problems of Newtonian mechanics.
Tidal analysis on a spreadsheet
Authors: de Levie Robert
Published: April 2004

A harmonic analysis of the tides combines astronomical data, Fourier transformation, and nonlinear least-squares analysis. Fourier transformation is used to display the power spectrum of the initial data and, during the subsequent refinement stages of the analysis, of the remaining residuals. Because only a relatively small sample is used, the frequency resolution of the Fourier transformation is insufficient to determine the precise frequencies involved, which are instead taken from astronomical data. The actual fitting of successive terms, in order of decreasing importance, is accomplished with nonlinear least squares. Because both Fourier transformation and nonlinear least-squares fitting are readily automated on a spreadsheet, the amount of computational effort required for this analysis is minimal.
Estimating the order of magnitude of derivatives in physics by means of characteristic lengths and times
Authors: Lorrain François
Published: April 2004

It is shown that, for many mathematical functions f or A used in physics, the order of magnitude of derivatives such as df/dt, dA/dt, ∇f, ∇⋅A, or ∇×A can be estimated relative to the order of magnitude of f or A, with the help of the characteristic times or characteristic lengths of f or A. This result provides a mathematical justification for the informal use of characteristic times and lengths often encountered in physics. The method is not applicable to all functions, however, and, when applicable, it cannot be applied blindly.
Bringing atomic and nuclear physics laboratory data into the classroom
Authors: Norman Eric B. , Larimer Ruth-Mary , Rech Gregory , Lee Jeffrey , Vue Chue , Leubane Tholoana , Zamvil Kenneth , Guthrie Laura
Published: April 2004

To illustrate a number of basic concepts in atomic and nuclear physics, we have developed three Web sites where students can analyze data from modern laboratories. By working through the on-line procedures, students will become acquainted with characteristic x-ray spectra, nuclear half-lives, x-ray fluorescence, and neutron activation analysis.
Series RC circuits revisited
Authors: Gordon J. E. , Grant P. R.
Published: April 2004

The measured and predicted properties of a series RC circuit containing a battery, a constant resistance R, and a time-dependent capacitance C are reported and compared with those of a conventional RC circuit with constant R and C and a time-dependent input voltage. The apparatus needed for these experiments is available in most undergraduate physics departments and the experiments are straightforward. Despite the simplicity of these circuits, some of the experimental results are unexpected. We describe several mathematical techniques that can be used to provide a detailed understanding of these results.
Schumann’s resonances: A particular example of a spherical resonant cavity
Authors: Ciappina M. F. , Febbo M.
Published: April 2004

The resonances between the Earth as one boundary and the ionosphere as the other, known as Schumann’s resonances, represent an interesting example of a spherical cavity. We consider a simple model in which the boundaries behave as perfect conductors and then take into account the finite conductivity of the boundaries. Numerical results are obtained for both models and compared with available data. Good agreement is shown to exist between the analytical results and the experimental values when finite conductivity of the walls is considered.
The role of hyperfine pumping in multilevel systems exhibiting saturated absorption
Authors: Smith David A. , Hughes Ifan G.
Published: April 2004

We study pump–probe spectroscopy of Rb vapor. Absorption spectra are presented for a weak probe beam in a room temperature vapor subject to a strong counter propagating pump beam of identical frequency. The importance of hyperfine pumping in the formation of the sub-Doppler spectrum is explained. For typical experimental parameters we clarify why the standard designation of “saturated absorption” spectroscopy is a misnomer. In contrast to saturated absorption, the details of the transient solution are crucial and hyperfine pumping leads to a modification of the absorption for detunings of many tens of natural linewidths from resonance.
Independent Cellular Processes for Hippocampal Memory Consolidation and Reconsolidation
Authors: Lee Jonathan L. C. , Everitt Barry J. , Thomas Kerrie L.
Published: April 2004

The idea that new memories undergo a time-dependent consolidation process after acquisition has received considerable experimental support. More controversial has been the demonstration that established memories, once recalled, become labile and sensitive to disruption, requiring “reconsolidation” to become permanent. By infusing antisense oligodeoxynucleotides into the hippocampus of rats, we show that consolidation and reconsolidation are doubly dissociable component processes of memory. Consolidation involves brain-derived neurotrophic factor (BDNF) but not the transcription factor Zif268, whereas reconsolidation recruits Zif268 but not BDNF. These findings confirm a requirement for BDNF specifically in memory consolidation and also resolve the role of Zif268 in brain plasticity, learning, and memory.
Conceptualisation, development, and evaluation of a measure of unplanned pregnancy
Authors: Barrett G , Smith S C , Wellings K
Published: April 2004

Study objective:To develop a measure of unplanned pregnancy that is valid, reliable, and appropriate in the context of contemporary demographic trends and social mores and can be used in a variety of situations, including the production of population prevalence estimates.

Design:A two stage study design: qualitative (inductive) methods to delineate the construct of pregnancy planning, and quantitative/psychometric methods to establish the means of measurement.

Setting:Eight health service providers (comprising 14 clinics, including antenatal, abortion, and one general practitioner) across London, Edinburgh, Hertfordshire, Salisbury, and Southampton in the UK.

Participants:Samples comprised a mixture of pregnant (continuing pregnancy and opting for abortion) and recently pregnant (post-abortion and postnatal) women. At the qualitative stage, 47 women took part in depth interviews (20 of whom were re-interviewed after the birth of their baby). Items were pre-tested with 26 women, and two psychometric field tests were carried out with, respectively, 390 and 651 women.

Main results:A six item measure of unplanned pregnancy was produced. Psychometric testing demonstrated the measure’s high reliability (Cronbach’s α = 0.92; test-retest reliability = 0.97) and high face, content, and construct validity. Women’s positions in relation to pregnancy planning are represented by the range of scores (0–12).

Conclusions:A psychometric measure of unplanned pregnancy, the development of which was informed by lay views, is now available. The measure is suitable for use with any pregnancy regardless of outcome (that is, birth, abortion, miscarriage) and is highly acceptable to women.
Medical decision making in scarcity situations
Authors: van Delden J J M , Vrakking A M , van der Heide A , van der Maas P J
Published: April 2004

The issue of the allocation of resources in health care is here to stay. The goal of this study was to explore the views of physicians on several topics that have arisen in the debate on the allocation of scarce resources and to compare these with the views of policy makers. We asked physicians (oncologists, cardiologists, and nursing home physicians) and policy makers to participate in an interview about their practices and opinions concerning factors playing a role in decision making for patients in different age groups. Both physicians and policy makers recognised allocation decisions as part of their reality. One of the strong general opinions of both physicians and policy makers was the rejection of age discrimination. Making allocation decisions as such seemed to be regarded as a foreign entity to the practice of medicine. In spite of the reluctance to make allocation decisions, physicians sometimes do. This would seem to be only acceptable if it is justified in terms of the best interests of the patient from whom treatment is withheld.
Applying a research ethics committee approach to a medical practice controversy: the case of the selective COX-2 inhibitor rofecoxib
Authors: James M J , Cleland L G
Published: April 2004

The new class of anti-inflammatory drugs, the COX-2 inhibitors, have been commercially successful to the point of market dominance within a short time of their launch. They attract a price premium on the basis that they are associated with fewer adverse gastric events than traditional anti-inflammatory drugs. This marketing continues even though a pivotal safety study with one of the COX-2 inhibitors, rofecoxib, showed a significant increase in myocardial infarction with rofecoxib use compared with a traditional anti-inflammatory drug. This finding has led to a series of publications containing pooled analyses of existing data that both support and refute the possibility of increased cardiovascular risk with COX-2 inhibitors.

These medical journal publications have served to obfuscate rather than provide guidance for medical practitioners. Consideration of a research ethics committee approach to this issue suggests that it would deal with the controversy in a straightforward manner—namely, it would simply inform research participants of the trial results with rofecoxib. The certainty of this research ethics committee approach raises the issue of whether it should be applied in normal medical practice outside of the research environment. A consideration of the legal tests for disclosure of information suggests that therapeutic medical practice should mirror that within the research environment, in this case.
Facing requests for euthanasia: a clinical practice guideline
Authors: Gastmans C , Van Neste F , Schotsmans P
Published: April 2004

On 23 September 2002, the Belgian law on euthanasia came into force. This makes Belgium the second country in the world (after the Netherlands) to have an Act on euthanasia. Even though there is currently legal regulation of euthanasia in Belgium, very little is known about how this legal regulation could be translated into care for patients who request euthanasia.
The standard of care debate: the Declaration of Helsinki versus the international consensus opinion: Table 1
Authors: Lie R K , Emanuel E , Grady C , Wendler D
Published: April 2004

The World Medical Association’s revised Declaration of Helsinki endorses the view that all trial participants in every country are entitled to the worldwide best standard of care. In this paper the authors show that this requirement has been rejected by every national and international committee that has examined this issue. They argue that the consensus view now holds that it is ethically permissible, in some circumstances, to provide research participants less than the worldwide best care. Finally, the authors show that there is also consensus regarding the broad conditions under which this is acceptable.
Current epistemological problems in evidence based medicine
Authors: Ashcroft R E
Published: April 2004

Evidence based medicine has been a topic of considerable controversy in medical and health care circles over its short lifetime, because of the claims made by its exponents about the criteria used to assess the evidence for or against the effectiveness of medical interventions. The central epistemological debates underpinning the debates about evidence based medicine are reviewed by this paper, and some areas are suggested where further work remains to be done. In particular, further work is needed on the theory of evidence and inference; causation and correlation; clinical judgment and collective knowledge; the structure of medical theory; and the nature of clinical effectiveness.
Ethical issues of cost effectiveness analysis and guideline setting in mental health care
Authors: Berghmans R , Berg M , van den Burg M , ter Meulen R
Published: April 2004

This article discusses ethical issues which are raised as a result of the introduction of economic evidence in mental health care in order to rationalise clinical practice. Cost effectiveness studies and guidelines based on such studies are often seen as impartial, neutral instruments which try to reduce the influence of non-scientific factors. However, such rationalising instruments often hide normative assumptions about the goals of treatment, the selection of treatments, the role of the patient, and the just distribution of scarce resources. These issues are dealt with in the context of increased control over clinical practice by third parties. In particular, health insurers have a great interest in economic evidence in clinical care settings in order to control access to and quality of (mental) health care. The authors conclude that guideline setting and cost effectiveness analysis may be seen as important instruments for making choices in health care, including mental health care, but that such an approach should always go hand in hand with a social and political debate about the goals of medicine and (mental) health care. This article is partly based on the results of a research project on the normative aspects of guideline setting in psychiatry and cardiology which was conducted under the guidance of the Royal Dutch Medical Association.
Evidence based medicine and justice: a framework for looking at the impact of EBM upon vulnerable or disadvantaged groups
Authors: Rogers W A
Published: April 2004

This article examines the implicit promises of fairness in evidence based medicine (EBM), namely to avoid discrimination through objective processes, and to distribute effective treatments fairly. The relationship between EBM and vulnerable groups (such as those disadvantaged by virtue of poverty, ethnicity, age, gender, mental health problems or similar) is examined. Several aspects of EBM are explored: the way evidence is created (commissioning and design of, and participation in research), and the way evidence is applied in clinical care and health policy. This analysis suggests that EBM turns our attention away from social and cultural factors that influence health and focuses on a narrow biomedical and individualistic model of health. Those with the greatest burden of ill health are left disenfranchised, as there is little research that is relevant to them, there is poor access to treatments, and attention is diverted away from activities that might have a much greater impact on their health.
Systemic cytomegalovirus infection complicating ulcerative colitis: a case report and review of the literature
Authors: Hamlin P J , Shah M N , Scott N , Wyatt J I , Howdle P D
Published: April 2004

Cytomegalovirus is a common infection worldwide and in the immunocompromised individual it can be a major cause of morbidity and mortality. In patients with inflammatory bowel disease cytomegalovirus infection has been described in both immunocompetent and immunocompromised individuals. A 34 year old man with an exacerbation of his colitis was diagnosed as having both cytomegalovirus colitis and hepatitis. The diagnosis was made on the classical appearance of “owl’s eye” inclusion bodies on colonic and hepatic biopsies and, in addition, viral serology and polymerase chain reaction (PCR) analysis of the cytomegalovirus DNA copy number. Fourteen days of treatment with ganciclovir led to a prompt improvement in the symptoms of colitis, resolution of the pyrexia, normalisation of the liver function tests, and clearance of the virus, as measured by a negative cytomegalovirus DNA PCR.

Cytomegalovirus infection is a potentially fatal complication of treatment induced immunosuppression in patients with inflammatory bowel disease. As in this case, infection may be systemic and not confined to the intestine. Prompt diagnosis using histology, serology, and PCR analysis allows prompt introduction of therapy and an improved prognosis.
Metformin induced acute pancreatitis precipitated by renal failure
Authors: Mallick S
Published: April 2004

Metformin is a biguanide commonly used in type 2 diabetes and considered to be a safe drug with minimal side effects. Approximately 2% of cases of acute pancreatitis may be caused by drugs, but it is not a known complication of metformin therapy. To date only one case of pancreatitis has been reported in association with metformin, but that was secondary to metformin poisoning (overdose). This is the first reported case of pancreatitis caused by a therapeutic dose of metformin (although in this case renal failure precipitated the metformin toxicity). Severe lactic acidosis is a rare but life threatening complication of metformin, which occurs particularly in patients with renal failure.
Management of inflammatory bowel disease
Authors: Nayar M , Rhodes J M
Published: April 2004

Ulcerative colitis and Crohn’s disease result from an interaction between genetic and environmental factors. Only one gene, NOD2/CARD15, has been clearly identified; a minority of people with alteration of this gene develop Crohn’s disease. The NOD2/CARD15 protein is thought to be involved in defence against intracellular bacteria. This supports the idea that Crohn’s disease and ulcerative colitis result from altered immunological responses to the normal intestinal flora. Life expectancy is normal in ulcerative colitis and nearly so in Crohn’s disease, but both conditions cause considerable morbidity. Approximately 80% of patients with Crohn’s disease eventually require surgery, and about 25% of patients with ulcerative colitis require colectomy. Treatment of ulcerative colitis is generally by corticosteroids for acute disease and mesalazine for maintenance, but the range of therapies for Crohn’s disease is expanding. Alternative therapies include immunosuppressives, enteral nutrition, antibiotics, anti-TNF antibody (infliximab), corticosteroids, and surgery. High dosages of corticosteroids may provide symptomatic relief in Crohn’s disease but do not affect the long term natural history of the disease, and management strategies should avoid using steroids whenever possible.
Evidence for ERK1/2 phosphorylation controlling contact inhibition of proliferation in Madin-Darby canine kidney epithelial cells
Authors: Li Shixiong , Gerrard Edward R. , Balkovetz Daniel F.
Published: April 2004

Increasing cell density arrests epithelial cell proliferation by a process termed contact inhibition. We investigated mechanisms of contact inhibition using a model of contact-inhibited epithelial cells. Hepatocyte growth factor (HGF) treatment of contact-inhibited Madin-Darby canine kidney (MDCK) cells stimulated cell proliferation and increased levels of phosphorylated ERK1/2 (phospho-ERK1/2) and cyclin D1. MEK inhibitors PD-98059 and U0126 inhibited these HGF-dependent changes, indicating the dependence on phosphorylation of ERK1/2 during HGF-induced loss of contact inhibition. In relation to contact-inhibited high-density cells, low-density MDCK cells proliferated and had higher levels of phospho-ERK1/2 and cyclin D1. PD-98059 and U0126 inhibited low-density MDCK cell proliferation. Trypsinization of high-density MDCK cells immediately increased phospho-ERK1/2 and was followed by a transient increase in cyclin D1 levels. Reformation of cell junctions after trypsinization led to decreases in phospho-ERK1/2 and cyclin D1 levels. High-density MDCK cells express low levels of both cyclin D1 and phospho-ERK1/2, and treatment of these cells with fresh medium containing HGF but not fresh medium alone for 6 h increased phospho-ERK1/2 and cyclin D1 levels compared with cells without medium change. These data provide evidence that HGF abrogates MDCK cell contact inhibition by increasing ERK1/2 phosphorylation and levels of cyclin D1. These results suggest that in MDCK cells, contact inhibition of cell proliferation in the presence of serum occurs by cell density-dependent regulation of ERK1/2 phosphorylation.
A dileucine motif targets the sulfate anion transporter sat-1 to the basolateral membrane in renal cell lines
Authors: Regeer Ralf R. , Markovich Daniel
Published: April 2004

The sat-1 transporter mediates sulfate/bicarbonate/oxalate anion exchange in vivo at the basolateral membrane of the kidney proximal tubule. In the present study, we show two renal cell lines [Madin-Darby canine kidney (MDCK) and porcine proximal tubular kidney (LLC-PK1) cells] that similarly target sat-1 exclusively to the basolateral membrane. To identify possible sorting determinants, we generated truncations of the sat-1 cytoplasmic COOH terminus, fused to enhanced green fluorescence protein (EGFP) or the human IL-2 receptor α-chain (Tac) protein, and both fusion constructs were transiently transfected into MDCK cells. Confocal microscopy revealed that removal of the last three residues on the sat-1 COOH terminus, a putative PDZ domain, had no effect on basolateral sorting in MDCK cells or on sulfate transport in Xenopus oocytes. Removal of the last 30 residues led to an intracellular expression for the GFP fusion protein and an apical expression for the Tac fusion protein, suggesting that a possible sorting motif lies between the last 3 and 30 residues of the sat-1 COOH terminus. Elimination of a dileucine motif at position 677/678 resulted in the loss of basolateral sorting, suggesting that this motif is required for sat-1 targeting to the basolateral membrane. This posttranslational mechanism may be important for the regulation of sulfate reabsorption and oxalate secretion by sat-1 in the kidney proximal tubule.