bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors influencing local abundance and haulout behaviour of ringed seals (Phoca hispida) on landfast ice of the Alaskan Beaufort Sea
Authors: Moulton Valerie D , Richardson W John , McDonald Trent L , Elliott Robert E , Williams Michael T
Published: January 2003

This study investigates how the local abundance of ringed seals (Phoca hispida) on landfast ice of the central Alaskan Beaufort Sea is related to habitat factors and how the haulout behaviour of seals is influenced by temporal and weather factors. An understanding of these relationships is required before the potential impacts of industrial activity on ringed seals can be assessed. Intensive and replicated aerial surveys employing strip transect methodology were conducted during the springs of 19971999. Data were examined with χ2 tests and Poisson regression. The overall observed densities of ringed seals over water depths >3 m was 0.43, 0.39, and 0.63 seals/km2 in 19971999, respectively. Significantly more seals occurred over intermediate water depths, especially 1020 m. In all years, seals were widely distributed on the landfast ice, but during breakup, higher numbers of seals occurred near the ice edge. Densities were significantly lower in areas with high ice deformation and extensive melt water. There was no consistent relationship between seal sightings and time of day within the 10:0018:00 period with surveys. The peak period of haulout occurred around 1 and 2 June. Significantly more ringed seals were observed on warm, cloudy days. There was no indication that limited winter industrial activity, including ice roads and Vibroseis, occurring within the study area in 19971999 significantly affected ringed seal density in spring.
Human disturbance, nursing behaviour, and lactational pup growth in a declining southern elephant seal (Mirounga leonina) population
Authors: Engelhard Georg H , Baarspul Antonie N.J , Broekman Martijn , Creuwels Jeroen C.S , Reijnders Peter J.H
Published: January 2003

We studied lactation behaviour in relation to pup growth in southern elephant seals (Mirounga leonina) at Macquarie Island, and compared harems in areas of high and low human presence to determine if there is an effect attributable to human activities, including scientific research. Pup weaning mass, a known correlate of firstyear survival, was positively influenced by suckle bout durations during early and middle lactation and by maternal aggression during late lactation; no other behavioural variables were associated with weaning mass. In the area of high human presence, we observed from a distance the behaviour of motherpup pairs directly before, during, and after visits to harems by other researchers. Alertness was raised threefold in the presence of people but quickly returned to predisturbance levels after their departure; there were no significant short-term effects on other behavioural variables. In the areas of high and low human presence, we observed the undisturbed behaviour of the seals in the absence of other people. No significant differences in any behavioural variables examined were found, indicating no long-term changes in behaviour resulting from human presence. Human disturbance therefore appears not to have significantly contributed to the population decline observed at Macquarie Island, but the conclusion requires caution given the fairly low power of our analyses.
The relation of body size of male humpback whales to their social roles on the Hawaiian winter grounds
Authors: Spitz Scott S , Herman Louis M , Pack Adam A , Deakos Mark H
Published: January 2003

We examined the relation of body length of male humpback whales (Megaptera novaeangliae) to the social roles they adopted on the Hawaiian winter grounds: principal escort in a competitive group, secondary escort, lone escort to a mothercalf pair, male partner in a dyad, and singer. Using underwater videogrammetry, we measured body lengths of 17 principal escorts, 68 secondary escorts, 40 single escorts, 17 male partners, and 8 singers. Results revealed that (i) principal escorts were, on average, significantly larger than males in each of the remaining social roles except singer, (ii) singers were significantly larger than male partners, (iii) there were no significant size differences among secondary escorts, single escorts, or male partners. Further, principal escorts tended to be the largest or second-largest male within their individual competitive group. All principal escorts were of sizes that indicated a 0.81 probability or better of sexual maturity, based on whaling data. In comparison, more than half of the male partners, almost one-third of the secondary escorts, and one-fifth of the single escorts were of sizes that indicated a 0.5 probability or less of sexual maturity. Seven of the eight singers had a 0.9 probability or better of sexual maturity and the eighth singer a 0.5 probability. However, the data for singers are too few to allow firm conclusions to be reached about the relation of body size to singing. Overall, our findings suggest that body size confers an advantage in physical competition between male humpback whales, and that a large proportion of males adopting the role of secondary escort, single escort, and partner are likely to be sexually immature. Additionally, the competitive group appears to be a major reproductive unit in terms of bringing together a receptive female and potential mates.
Sex-specific intertidal habitat use in subtropically wintering Bar-tailed Godwits
Authors: Zharikov Yuri , Skilleter Gregory A
Published: January 2003

Habitat use by sexually dimorphic Bar-tailed Godwits (Limosa lapponica) was examined in an Australian estuary during the midwintering (NovemberDecember) and premigratory (March) periods of a nonbreeding season. In an area with two available habitats, Zostera seagrass beds and unvegetated sand flats, males occurred almost exclusively in seagrass, whereas the females occurred at equal densities in both habitats. Estimates of intake rates seemed greater for individuals foraging in seagrass (0.1140.128 g dry mass (DM)·min1) than on sand (0.0640.087 g DM·min1). Males appeared less well adapted for foraging on sand than in seagrass, and the presence of females could interfere with males' foraging on sand. The reason for the equal distribution of the females between the habitats probably lies in the inability of one particular habitat to support the entire population of females. Little interhabitat movement by individuals was detected. Within a habitat, sexes moved synchronously at the 1-ha scale but showed a degree of segregation at the individual scale, suggesting that some avoidance existed. Three diet types were observed in the godwits in the area: (1) dominated by soldier crabs (Mictyris longicarpus) on sand, (2) dominated by sentinel crabs (Macrophthalmus spp.) in seagrass, and (3) dominated by soft-bodied prey in seagrass.
Heart and aorta morphology of the deep-diving hooded seal (Cystophora cristata)
Authors: Drabek Charles M , Burns Jennifer M
Published: January 2003

An investigation of the heart morphology of 8 male and 15 female hooded seals (Cystophora cristata) revealed that the heart is proportionately large and the aortic bulb is larger than that reported for most seals. Hooded seals of all ages have large hearts (0.64% of the body mass) and the right ventricle is proportionately longer and more muscular than reported for other seals. The bulb of the ascending aorta shows the large-diameter characteristic of seals capable of making long deep dives, and is constricted to a diameter of less than one-third in the descending aorta. In addition, the ascending aorta has a much greater concentration of elastin fibers than does the descending aorta. In combination with the large right ventricle, these features probably serve to increase lung perfusion during the hooded seal's surface recovery, and to maintain a high blood pressure throughout the cardiac cycle during diving bradycardia. That there was no substantive difference in the heart morphology of pups, yearlings, and adults, suggests that these features are important in the development of diving behavior, and agrees with the rapid behavioral and physiological development of hooded seal neonates.
Inbreeding, outbreeding, infant growth, and size dimorphism in captive Indian rhinoceros (Rhinoceros unicornis)
Authors: Zschokke Samuel , Baur Bruno
Published: January 2003

Effects of inbreeding and outbreeding on gestation period, birth mass, infant mortality, and growth, as well as the ontogeny of sexual size dimorphism, were analyzed in captive Indian rhinoceros (Rhinoceros unicornis L., 1758) using studbook data. Neither gestation period nor birth mass were affected by inbreeding. However, inbred calves grew slower and had a lower mortality rate than non-inbred ones. It is suggested that the severe bottleneck experienced in the early twentieth century by the Kaziranga population, from which most captive-born Indian rhinoceroses descend, resulted in strong inbreeding with consequent purging of recessive lethal alleles. Outbred individuals (offspring of matings between individuals from the Kaziranga and the Chitwan populations) had a higher infant mortality rate, suggesting that the two populations are genetically partially incompatible. Among captive individuals, adult males were found to be heavier (2300 kg) and larger (shoulder height = 172 cm) than females (1800 kg, 160 cm). There were, however, no sex differences in gestation period, birth mass, or infant growth. This suggests that sexual dimorphism in adults is the result of a longer growth period in males rather than a difference in growth rate between the sexes.
Microsatellite analysis of multiple paternity and male reproductive success in the promiscuous snowshoe hare
Authors: Burton Cole
Published: January 2003

Few genetic studies have addressed patterns of paternity in promiscuous mammals. I used microsatellite DNA primers developed in the European rabbit to analyze paternity in the promiscuous snowshoe hare (Lepus americanus). Sixty-five offspring, their 12 mothers, and their 24 putative fathers were genotyped at seven polymorphic loci (322 alleles/locus). Paternal allele counts and likelihood-based paternity assignments confirmed that multiple paternity occurs in snowshoe hare litters. However, the estimated frequency of multiple paternity was lower than expected in an unstructured promiscuous mating system. A relatively low variance in male reproductive success indicated that no males dominated paternity. A few males did achieve significantly more paternities than average, largely by fathering one or two complete litters rather than a few offspring in many litters. The results suggest that successful multiple mating is limited among both male and female snowshoe hares. An important role for pre- and (or) post-copulatory competition is implied.
Factors shaping the parasite communities of trout-perch, Percopsis omiscomaycus Walbaum (Osteichthyes: Percopsidae), and the importance of scale
Authors: Nelson Patrick A , Dick Terry A
Published: January 2003

Trout-perch (Percopsis omiscomaycus Walbaum) provide a useful model in which to study fish-parasite communities because they have restricted trophic categories, they represent a single widely distributed taxon in North America, and numerous compound community surveys exist for comparison at the local and biogeographical scales. Forty-two species are reported from trout-perch, with 19 species known from Dauphin Lake, Manitoba, Canada. The most prevalent parasites species increased with host age, relating to increased food intake and (or) shifts in dietary preference towards larger food items. Randomization methods developed here demonstrate observed richness, and diversity patterns are nonrandom for local infracommunities and regional component communities. High mean overlaps, combined with high number of shared parasites and diversity estimates, indicate a predictable system. Schooling, maximum size, and age restricted the trout-perch diets to macroinvertebrates, resulting in extensive dietary sharing, which produced their homogenous infracommunities. Inshoreoffshore diurnal movements combined with limited trophic categories revealed predictable component communities at the biogeographical scale. Eight parasites were predictable at the local scale and six at the regional scale (comprising two strictly host-specific species and four ecological species). Ecological predictability was determined by repeated predatorprey patterns, preferred host habitat, and niche sympatry. Trout-perch parasite communities, at both the local and regional scales, were determined by stable infracommunity processes and fish community complexity, which influence the component communities at the local scale.
Thermoregulatory accuracy, precision, and effectiveness in two sand-dwelling lizards under mild environmental conditions
Authors: Sartorius Shawn S , do Amaral José P.S , Durtsche Richard D , Deen Cari M , Lutterschmidt William I
Published: January 2003

We investigated thermoregulation and habitat use in two sympatric lizard species of the family Phrynosomatidae (side-blotched lizards, Uta stansburiana, and sand-dune lizards, Sceloporus arenicolus) in southern New Mexico to determine whether thermoregulation was necessary and detectable under mild temperature conditions, and what behavioral mechanisms the lizards used to thermoregulate throughout their daily activity. We measured lizard temperature preference (Tsel) in a laboratory thermal gradient as well as field body temperature (Tb) at the study site. We then calculated several indices of thermoregulation to evaluate the effectiveness of thermoregulation for both species. In addition, we recorded and compared micro- and macro-habitat use for the two species; we also compared these habitats with randomly selected microsites. Uta stansburiana thermoregulated less precisely in a laboratory gradient than did S. arenicolus and had a slightly higher preferred temperature. Environmental thermal heterogeneity occurred at both micro- and macro-habitat spatial scales, allowing lizards to thermoregulate optimally for over 10 h/day. The two species maintained mean body temperatures within their selected temperature range throughout most of the day. Two indices of thermoregulatory effectiveness revealed that both species are effective thermoregulators, and thermoregulation was easily detectable throughout the day. Lizards used the behavioral mechanisms of microhabitat choice, posture, shuttling between sun and shade, and orientation to the sun to regulate Tb.
Development of the muskox lungworm, Umingmakstrongylus pallikuukensis (Protostrongylidae), in gastropods in the Arctic
Authors: Kutz Susan J , Hoberg Eric P , Nishi John , Polley Lydden
Published: January 2003

Development of the muskox protostrongylid lungworm, Umingmakstrongylus pallikuukensis, in its slug intermediate host, Deroceras laeve, was investigated under field conditions in the Arctic. Every 2 weeks, from 19 June to 28 August 1997, groups of 10 experimentally infected slugs were placed in tundra enclosures in a mesic sedge meadow near Kugluktuk, Nunavut, Canada. First-stage larvae (L1) infecting slugs on or before 17 July developed to third-stage larvae (L3) in 46 weeks. Intensity of L3 in slugs peaked at 68 weeks post infection (PI) and then progressively declined by 10, 12, and 4850 weeks PI. Abundance of L3 in slugs was greatest during mid to late August. L1 infecting slugs on 31 July or later did not develop to L3 before the end of September but overwintered in slugs on the tundra as L1 or as second-stage larvae, completing development to L3 the following summer. The years 1997 and 1998 were exceptionally warm and, in cooler years, rates of larval development may be slower and patterns of availability may differ. The amount of heating (degree-days) accumulated during each trial was calculated using the 8.5°C threshold determined in the laboratory, a 21°C maximum, and either surface, soil, or air temperature. Only degree-days accumulated at the surface were sufficient to correspond to the observed rates of larval development. This enclosure-based system and associated degree-day calculations may be used for predicting the effects of climate and climate change on patterns of parasite development and transmission in the Arctic.
TESTING GRAVITY IN LARGE EXTRA DIMENSIONS USING BOSE–EINSTEIN CONDENSATES
Authors: SIGURDSSON STEINN
Published: January 2003

Recent conjectures that there are mesoscopically "large" extra dimensions, through which gravity propagates have interesting implications for much of physics. The scenario implies gross departures from Newton's law of gravity at small length scales. Testing departures from Coulomb's law on sub-millimetre scales is hard.

It is now possible to routinely create Bose–Einstein condensates with de Broglie wavelengths of order a μm and total size of order 10 μm. BEC condensates move coherently under gravitational acceleration, and I propose that the transverse fringe shift due to the acceleration of a pair of interfering BECs passing a dense linear mass may be measurable, and provide direct evidence for anomalous gravitational acceleration. Ideally such experiments are best carried out in free fall to maximise the time spent by a BEC in the non-Newtonian regime.
TWILIGHT FOR THE ENERGY CONDITIONS?
Authors: BARCELÓ CARLOS , VISSER MATT
Published: January 2003

The tension, if not outright inconsistency, between quantum physics and general relativity is one of the great problems facing physics at the turn of the millennium. Most often, the problems arising in merging Einstein gravity and quantum physics are viewed as Planck scale issues (1019 GeV , 10-34 m , 10-45 s ), and so safely beyond the reach of experiment. However, over the last few years it has become increasingly obvious that the difficulties are more widespread: There are already serious problems of deep and fundamental principle at the semi-classical level, and worse, certain classical systems (inspired by quantum physics, but in no sense quantum themselves) exhibit seriously pathological behaviour. One manifestation of these pathologies is in the so-called "energy conditions" of general relativity. Patching things up in the gravity sector opens gaping holes elsewhere; and some "fixes" are more radical than the problems they are supposed to cure.
CASIMIR FORCE BETWEEN A GRAVITATIONAL FIELD AND A FINITE OBJECT
Authors: PINTO FABRIZIO
Published: January 2003

In the typical Casimir effect, the boundaries of two semi-infinite media exert a force upon one another across a vacuum gap separating them. In this paper, I argue that a static gravitational field can be regarded as a "soft" boundary which interacts with a test object of finite size through the electromagnetic zero-point-energy field. Therefore, a pressure exists upon a single slab placed in a gravitational field and surrounded by a vacuum. Interestingly, this extremely small Casimir pressure of the gravitational field may cause relative displacements in ground-based sensing microstructures larger than those from astrophysical gravitational waves in macroscopic antennas.
THE FULLING–DAVIES–UNRUH EFFECT IS MANDATORY: THE PROTON'S TESTIMONY
Authors: MATSAS GEORGE E. A. , VANZELLA DANIEL A. T.
Published: January 2003

We discuss the decay of accelerated protons and illustrate how the Fulling–Davies–Unruh effect is indeed mandatory to maintain the consistency of standard Quantum Field Theory. The confidence level of the Fulling–Davies–Unruh effect must be the same as that of Quantum Field Theory itself.
FERMION FAMILIES AND LONG-RANGE FORCE PROBLEMS: INTERRELATION AND RESOLUTION
Authors: GUENDELMAN E. I. , KAGANOVICH A. B.
Published: January 2003

We study a generally covariant model with SSB of scale invariance where two measures of integration in the action enter: the standard [Formula: see text] and a new Φd4x, where Φ is a density built out of degrees of freedom independent of the metric. Under normal laboratory conditions where the fermionic matter dominates, it is found that starting from a single fermionic field we obtain exactly three different types of spin 1/2 particles which can be identified with known fermion families. It is automatically achieved that for two of them, fermion masses are constants, the energy-momentum tensor is canonical and the "fifth force" is absent. For the third family, a self-interaction appears as a result of SSB of scale invariance.
BRANE–ANTIBRANE INFLATION
Authors: BURGESS C. P.
Published: January 2003

Inflationary cosmology has become central to our understanding of the initial conditions on whose foundations the current successes of the Hot Big Bang model rest. This is despite the well-known difficulties in finding systems whose dynamics naturally provide all of the features which successful inflation demands. Although string theory provides our best description of the physics of the relevant energy scales, it has only recently begun to shed insight into what the inflationary dynamics might be: the physics of brane-antibrane collisions. This essay is meant to summarize the difficulties which have blocked this realization until now, as well as the new insights about inflation which are now beginning to emerge.
CHANGING ALPHA: SOME MATTERS OF GRAVITY
Authors: BARROW JOHN D. , MAGUEIJO JOÃO , SANDVIK HÅVARD BUNES
Published: January 2003

We show how recent evidence for a small cosmological variation of the fine structure "constant" can be tested by local experiments which probe the behaviour of gravity. In particular, in the simplest theory, 'fifth force' experiments should see a positive effect with just an order of magnitude increase in current sensitivity. Space experiments should easily see the predicted effects.
HIERARCHY PROBLEM IN THE SHELL-UNIVERSE MODEL
Authors: GOGBERASHVILI MERAB
Published: January 2003

In the model where the Universe is considered as a thin shell expanding in five-dimensional hyper-space there is a possibility to obtain one scale for particle theory corresponding to the five-dimensional cosmological constant and Universe thickness.
GRAVITATIONAL TRAPPING FOR EXTENDED EXTRA DIMENSION
Authors: GOGBERASHVILI MERAB
Published: January 2003

The solution of Einstein's equations for 4-brane embedded in five-dimensional Anti-de Sitter space–time is found. It is shown that the cosmological constant can provide the existence of ordinary four-dimensional Newton's law and trapping of a matter on the brane.
DOUBLY-SPECIAL RELATIVITY: FIRST RESULTS AND KEY OPEN PROBLEMS
Authors: AMELINO-CAMELIA GIOVANNI
Published: January 2003

I examine the results obtained so far in exploring the recent proposal of theories of the relativistic transformations between inertial observers that involve both an observer-independent velocity scale and an observer-independent length/momentum scale. I also discuss what appear to be the key open issues for this research line.
ON THE SPIN OF GRAVITATIONAL BOSONS
Authors: AHLUWALIA D. V. , DADHICH N. , KIRCHBACH M.
Published: January 2003

We unearth spacetime structure of massive vector bosons, gravitinos, and gravitons. While the curvatures associated with these particles carry a definite spin, the underlying potentials cannot be, and should not be, interpreted as single spin objects. For instance, we predict that a spin measurement in the rest frame of a massive gravitino will yield the result 3/2 with probability one half, and 1/2 with probability one half. The simplest scenario leaves the Riemannian curvature unaltered; thus avoiding conflicts with classical tests of the theory of general relativity. However, the quantum structure acquires additional contributions to the propagators, and it gives rise to additional phases.
CONSTRAINTS ON COSMIC EQUATION OF STATE USING GRAVITATIONAL LENSING STATISTICS WITH EVOLVING GALAXIES
Authors: DEV ABHA , JAIN DEEPAK , PANCHAPAKESAN N. , MAHAJAN S. , BHATIA V. B.
Published: January 2003

In this paper, observational constraints on the cosmic equation of state of dark energy (p = wρ) have been investigated using gravitational lensing statistics. A likelihood analysis of the lens survey has been carried out to constrain the cosmological parameters Ωmand w. Constraints on Ωmand w are obtained in three different models of galaxy evolution: no evolution model (comoving number density of galaxies remain constant), Volmerange and Guiderdoni Model and fast merging model. The last two models consider the number evolution of galaxies in addition to the luminosity evolution. The likelihood analysis shows that for the no-evolution case w ≤ -0.04 and Ωm≤ 0.90 at 1σ (68% confidence level (CL)). Similarly for the Volmerange & Guiderdoni Model the constraints are w ≤ -0.04 and Ωm≤ 0.91 at 1σ. In fast merging model the constraint become weaker and it allows almost the entire range of parameters. For the case of constant Λ (w = -1), all the models permit Ωm= 0.3 with 68% CL, which is consistent with the value of Ωminferred from various other cosmological observations.
ENERGY EXTRACTION FROM GRAVITATIONAL COLLAPSE TO STATIC BLACK HOLES
Authors: RUFFINI REMO , VITAGLIANO LUCA
Published: January 2003

The mass-energy formula of black holes implies that up to 50% of the energy can be extracted from a static black hole. Such a result is reexamined using the recently established analytic formulas for the collapse of a shell and the expression for the irreducible mass of a static black hole. It is shown that the efficiency of energy extraction process during the formation of the black hole is linked in an essential way to the gravitational binding energy, the formation of the horizon and the reduction of the kinetic energy of implosion. Here a maximum efficiency of 50% in the extraction of the mass energy is shown to be generally attainable in the collapse of a spherically symmetric shell: surprisingly this result holds as well in the two limiting cases of the Schwarzschild and extreme Reissner–Nordström space–times. Moreover, the analytic expression recently found for the implosion of a spherical shell to an already formed black hole leads to a new exact analytic expression for the energy extraction which results in an efficiency strictly less than 100% for any physical implementable process. There appears to be no incompatibility between General Relativity and Thermodynamics at this classical level.
Incremental Value of Ultrasonic Tissue Characterization (Backscatter) in the Evaluation of Left Ventricular Myocardial Structure and Mechanics in Essential Arterial Hypertension
Authors: Di Bello Vitantonio , Giorgi Davide , Talini Enrica , Dell’ Omo Giulia , Palagi Caterina , Romano Maria Francesca , Pedrinelli Roberto , Mariani Mario
Published: January 2003

Background—

Ultrasonic backscatter parameters were analyzed in hypertensive patients and divided into groups according to both severity of left ventricular hypertrophy (LVH) (group A: no LVH [n=52]; B: mild to moderate LVH [n=55]; and C: severe LVH [n=10]) and left ventricular geometry (normal geometry [n=44]; concentric remodeling [n=8]; concentric hypertrophy [n=25]; and eccentric hypertrophy [n=40]).

Methods and Results—

We studied 117 male, essential hypertensive patients and 19 normotensive, age-matched (40±5 years), healthy subjects who served as controls. Ambulatory and office blood pressure measurements were taken and 2-dimensional Doppler echocardiography and ultrasonic myocardial integrated backscatter (IBS) were performed. A group from the hypertensive study population (n=16) was observed after a period of pharmacological antihypertensive treatment to determine the behavior of backscatter parameters in relation to eventual regression of left ventricular mass (LVM). The cyclic variation index (CVIs) of the backscatter signal at the septum level was grouped according to each LVM level and was 29.4±9.3 (controls), 15±11 (group A), 9.5±10 (group B), and −1.5±8.6 (group C) (
P
<0.001). CVI septum values grouped according to left ventricular geometry were 15±11 (normal geometry), 12±7 (concentric remodeling), 7±11 (concentric hypertrophy), and 7.8±11 (eccentric hypertrophy) (
P
<0.01). Follow-up data demonstrate a significant reduction of LVM after therapy, as well as a significant increase in CVIs toward normal values.

Conclusions—

Hypertensive patients with higher LVM had the worst prognosis; in fact, those patients had the most significant CVI alterations. Regression of LVM subsequent to chronic pharmacological therapy induces a normalization of ultrasonic backscatter parameters. Ultrasonic tissue characterization (backscatter) analysis could allow early identification of patients at risk of developing complications of hypertensive cardiopathy.
Elevations of Inflammatory and Procoagulant Biomarkers in Elderly Persons With Renal Insufficiency
Authors: Shlipak Michael G. , Fried Linda F. , Crump Casey , Bleyer Anthony J. , Manolio Teri A. , Tracy Russell P. , Furberg Curt D. , Psaty Bruce M.
Published: January 2003

Background—

Renal insufficiency has been associated with cardiovascular disease events and mortality in several prospective studies, but the mechanisms for the elevated risk are not clear. Little is known about the association of renal insufficiency with inflammatory and procoagulant markers, which are potential mediators for the cardiovascular risk of kidney disease.

Methods and Results—

The cross-sectional association of renal insufficiency with 8 inflammatory and procoagulant factors was evaluated using baseline data from the Cardiovascular Health Study, a population-based cohort study of 5888 subjects aged ≥65 years. C-reactive protein, fibrinogen, factor VIIc, and factor VIIIc levels were measured in nearly all participants; interleukin-6, intercellular adhesion molecule-1, plasmin-antiplasmin complex, and D-dimer levels were measured in nearly half of participants. Renal insufficiency was defined as a serum creatinine level ≥1.3 mg/dL in women and ≥1.5 mg/dL in men. Multivariate linear regression was used to compare adjusted mean levels of each biomarker in persons with and without renal insufficiency after adjustment for other baseline characteristics. Renal insufficiency was present in 647 (11%) of Cardiovascular Health Study participants. After adjustment for baseline differences, levels of C-reactive protein, fibrinogen, interleukin-6, factor VIIc, factor VIIIc, plasmin-antiplasmin complex, and D-dimer were significantly greater among persons with renal insufficiency (
P
<0.001). In participants with clinical, subclinical, and no cardiovascular disease at baseline, the positive associations of renal insufficiency with these inflammatory and procoagulant markers were similar.

Conclusion—

Renal insufficiency was independently associated with elevations in inflammatory and procoagulant biomarkers. These pathways may be important mediators leading to the increased cardiovascular risk of persons with kidney disease.
Effect of Nasal Continuous Positive Airway Pressure Treatment on Blood Pressure in Patients With Obstructive Sleep Apnea
Authors: Becker Heinrich F. , Jerrentrup Andreas , Ploch Thomas , Grote Ludger , Penzel Thomas , Sullivan Colin E. , Peter J. Hermann
Published: January 2003

Background—

There is increasing evidence that obstructive sleep apnea (OSA) is an independent risk factor for arterial hypertension. Because there are no controlled studies showing a substantial effect of nasal continuous positive airway pressure (nCPAP) therapy on hypertension in OSA, the impact of treatment on cardiovascular sequelae has been questioned altogether. Therefore, we studied the effect of nCPAP on arterial hypertension in patients with OSA.

Methods and Results—

Sixty consecutive patients with moderate to severe OSA were randomly assigned to either effective or subtherapeutic nCPAP for 9 weeks on average. Nocturnal polysomnography and continuous noninvasive blood pressure recording for 19 hours was performed before and with treatment. Thirty two patients, 16 in each group, completed the study. Apneas and hypopneas were reduced by ≈95% and 50% in the therapeutic and subtherapeutic groups, respectively. Mean arterial blood pressure decreased by 9.9±11.4 mm Hg with effective nCPAP treatment, whereas no relevant change occurred with subtherapeutic nCPAP (
P
=0.01). Mean, diastolic, and systolic blood pressures all decreased significantly by ≈10 mm Hg, both at night and during the day.

Conclusions—

Effective nCPAP treatment in patients with moderate to severe OSA leads to a substantial reduction in both day and night arterial blood pressure. The fact that a 50% reduction in the apnea-hypopnea index did not result in a decrease in blood pressure emphasizes the importance of highly effective treatment. The drop in mean blood pressure by 10 mm Hg would be predicted to reduce coronary heart disease event risk by 37% and stroke risk by 56%.
Intravascular Ultrasound Guidance Improves Angiographic and Clinical Outcome of Stent Implantation for Long Coronary Artery Stenoses
Authors: Oemrawsingh Pranobe V. , Mintz Gary S. , Schalij Martin J. , Zwinderman Aeilko H. , Jukema J. Wouter , Wall Ernst E.v.d.
Published: January 2003

Background—

Long coronary lesions treated with stents have a poor outcome. This study compared the 6-month outcome of stent implantation for long lesions in patients randomized to intravascular ultrasound (IVUS; n=73) or angiographic guidance (n=71).

Methods and Results—

Stenoses >20 mm in length and a reference diameter that permitted a stent diameter ≥3 mm were eligible. Primary end points were 6-month minimal lumen diameter (MLD) and the combined end point of death, myocardial infarction, and target-lesion revascularization (TLR). Baseline clinical and angiographic data were comparable in both groups. At 6 months, MLD in the IVUS group (1.82±0.53 mm) was larger than in the angiography group (1.51±0.71 mm;
P
=0.042). TLR and combined end-point rates at 6 months were 4% (n=3) and 6% (n=4) in the IVUS group and 14% (n=10) and 20% (n=14) in the angiography group, respectively (
P
=0.037 for TLR and
P
=0.01 for combined events). Restenosis (>50% diameter stenosis) was found in 23% of the IVUS group and 45% of the angiography group (
P
=0.008). At 12 months, TLR and the combined end point occurred in 10% (n=7) and 12% (n=9) of the IVUS group and 23% (n=17) and 27% (n=19) of the angiography group (
P
=0.018 and
P
=0.026), respectively.

Conclusions—

Angiographic and clinical outcome up to 12 months after long stent placement guided by IVUS is superior to guidance by angiography.
Simvastatin Initiated Early After Heart Transplantation
Authors: Wenke Klaus , Meiser Bruno , Thiery Joachim , Nagel Dorothea , von Scheidt Wolfgang , Krobot Karl , Steinbeck Gerhard , Seidel Dietrich , Reichart Bruno
Published: January 2003

Background—

Randomized clinical trials have demonstrated that the use of statins in heart transplant patients lowers cholesterol levels and significantly reduces mortality and the development of transplant vasculopathy. The aim of the present study was to test these effects and the safety of statin therapy over an 8-year period.

Methods and Results—

In 1991, a prospective, randomized, unmasked study was initiated to compare the efficacy of simvastatin, started on the fourth postoperative day (n=35), with that of dietary therapy alone (n=37). Because of significantly improved survival and a lower incidence of transplant vasculopathy, most patients in both groups received statins as open-label prescriptions after 4 years. After 8 years, the Kaplan-Meier survival rate was 88.6% in the simvastatin group versus 59.5% in the control group (
P
<0.006 by log rank; hazard ratio, 0.24; 95% CI, 0.08 to 0.71). Deaths in the simvastatin and control groups were due to transplant vasculopathy (1 versus 4;
P
<0.2), severe transplant rejection (1 versus 5;
P
<0.1), malignancies (0 versus 3;
P
<0.1), and other causes (2 versus 3;
P
<0.7). The incidence of transplant vasculopathy confirmed by angiography was 24.4% in the simvastatin group versus 54.7% in the control group (
P
<0.02 by log rank). There was no difference in organ function between the 2 groups. No severe adverse effects of the therapy were observed up to the end of the 8-year observation period.

Conclusions—

Simvastatin therapy initiated early after heart transplantation leads to significantly better 8-year survival rates and a significantly lower incidence of transplant vasculopathy without impairment of organ function or severe adverse effects.
Sustained Hemodynamic Effects of Intravenous Levosimendan
Authors: Kivikko Matti , Lehtonen Lasse , Colucci Wilson S.
Published: January 2003

Background—

The short-term infusion of levosimendan (Levo) improves hemodynamic function in patients with decompensated heart failure. The metabolites of Levo have a prolonged half-life, and one is hemodynamically active. The goal of this study was to determine whether the hemodynamic effects of Levo are sustained during a long-term infusion and beyond the discontinuation of drug infusion.

Methods and Results—

Patients with decompensated heart failure received escalating infusion rates of intravenous Levo (n=98) or placebo (n=48) for 6 hours. At the end of 6 hours, 85 of the Levo-treated patients were continued on open-label drug for a total of 24 hours, at which time they were randomized 1:1 to an additional 24 hours of Levo (n=43) or placebo (n=42).The hemodynamic effects observed at 24 hours were maintained at 48 hours in both the continuation and withdrawal groups and did not differ between groups. Although the plasma concentration of Levo decreased rapidly in the withdrawal group, concentrations of the active metabolite OR-1896 were similar in the continuation and withdrawal groups at 24 hours and increased further (3.5-fold to 4-fold) and to a similar extent in both groups at 48 hours.

Conclusions—

The hemodynamic effects of Levo were maintained during a 48-hour continuous infusion and for at least 24 hours after discontinuation of a 24-hour infusion. The active metabolite OR-1896 increased for at least 24 hours after cessation of drug infusion and may account for the prolonged hemodynamic effects of Levo.
Modulation of Aspirin-Insensitive Eicosanoid Biosynthesis by 6-Methylprednisolone in Unstable Angina
Authors: Cipollone Francesco , Ganci Antonina , Greco Anita , Panara Maria Rosaria , Pasquale Massimo , Di Gregorio Domenico , Porreca Ettore , Mezzetti Andrea , Cuccurullo Franco , Patrignani Paola
Published: January 2003

Background—

The evidence that inflammation plays a pivotal role in the pathophysiology of acute coronary syndromes prompted us to investigate the effects of glucocorticoid treatment on leukotriene (LT) C
4
and thromboxane (TX) A
2
biosynthesis in unstable angina.

Methods and Results—

Urinary LTE
4
and 11-dehydro-TXB
2
were significantly higher in 12 patients with unstable angina than in 12 patients with stable angina and 12 patients with nonischemic chest pain. Furthermore, we randomized the unstable angina patients to receive intravenous 6-methylprednisolone (6-MP; 1 mg/kg BID for 2 days) or matching placebo and collected 12 consecutive 6-hour urine samples before and during the infusions. LTE
4
excretion showed a time-dependent decrease in the 6-MP group but did not decrease during placebo. Furthermore, during myocardial ischemia, LTE
4
was significantly higher before 6-MP infusion than during steroid therapy. In contrast, 11-dehydro-TXB
2
did not differ significantly during 6-MP versus placebo. Myocardial ischemia elicited by stress test in the stable angina patients was not accompanied by any change in LTE
4
and 11-dehydro-TXB
2
, thus ruling out a role of ischemia per se in the induction of increased eicosanoid production.

Conclusions—

Increased production of vasoactive LT and TX may occur in unstable angina despite conventional antithrombotic and antianginal treatment. Glucocorticoids can suppress LTC
4
biosynthesis in the short term and may provide an interesting tool to explore the pathophysiological significance of inflammatory cell activation in this setting.
Quantification of Macrophage Content in Atherosclerotic Plaques by Optical Coherence Tomography
Authors: Tearney Guillermo J. , Yabushita Hiroshi , Houser Stuart L. , Aretz H. Thomas , Jang Ik-Kyung , Schlendorf Kelly H. , Kauffman Christopher R. , Shishkov Milen , Halpern Elkan F. , Bouma Brett E.
Published: January 2003

Background—

Macrophage degradation of fibrous cap matrix is an important contributor to atherosclerotic plaque instability. An imaging technology capable of identifying macrophages in patients could provide valuable information for assessing plaque vulnerability. Optical coherence tomography (OCT) is a new intravascular imaging modality that allows cross-sectional imaging of tissue with a resolution of ≈10 μm. The aim of this study was to investigate the use of OCT for identifying macrophages in fibrous caps.

Methods and Results—

OCT images of 26 lipid-rich atherosclerotic arterial segments obtained at autopsy were correlated with histology. Cap macrophage density was quantified morphometrically by immunoperoxidase staining with CD68 and smooth muscle actin and compared with the standard deviation of the OCT signal intensity at corresponding locations. There was a high degree of positive correlation between OCT and histological measurements of fibrous cap macrophage density (
r
=0.84,
P
<0.0001) and a negative correlation between OCT and histological measurements of smooth muscle actin density (
r
=−0.56,
P
<0.005). A range of OCT signal standard deviation thresholds (6.15% to 6.35%) yielded 100% sensitivity and specificity for identifying caps containing >10% CD68 staining.

Conclusions—

The high contrast and resolution of OCT enables the quantification of macrophages within fibrous caps. The unique capabilities of OCT for fibrous cap characterization suggest that this technology may be well suited for identifying vulnerable plaques in patients.
TAXUS I
Authors: Grube Eberhard , Silber Sigmund , Hauptmann Karl Eugen , Mueller Ralf , Buellesfeld Lutz , Gerckens Ulrich , Russell Mary E.
Published: January 2003

Background—

The TAXUS NIRx stent (Boston Scientific Corp) provides local delivery of paclitaxel via a slow-release polymer coating. The TAXUS I trial was the first in-human experience evaluating safety and feasibility of the TAXUS NIRx stent system compared with bare NIR stents (control) (Boston Scientific Corp) for treatment of coronary lesions.

Methods and Results—

The TAXUS I trial was a prospective, double-blind, three-center study randomizing 61 patients with de novo or restenotic lesions (≤12 mm) to receive a TAXUS (n=31) versus control (n=30) stent (diameter 3.0 or 3.5 mm). Demographics, lesion characteristics, clinical outcomes were comparable between the groups. The 30-day major adverse cardiac event (MACE) rate was 0% in both groups (
P
=NS). No stent thromboses were reported at 1, 6, 9, or 12 months. At 12 months, the MACE rate was 3% (1 event) in the TAXUS group and 10% (4 events in 3 patients) in the control group (
P
=NS). Six-month angiographic restenosis rates were 0% for TAXUS versus 10% for control (
P
=NS) patients. There were significant improvements in minimal lumen diameter (2.60±0.49 versus 2.19±0.65 mm), diameter stenosis (13.56±11.77 versus 27.23±16.69), and late lumen loss (0.36±0.48 versus 0.71±0.48 mm) in the TAXUS group (all
P
<0.01). No evidence of edge restenosis was seen in either group. Intravascular ultrasound analysis showed significant improvements in normalized neointimal hyperplasia in the TAXUS (14.8 mm
3
) group compared with the control group (21.6 mm
3
) (
P
<0.05).

Conclusions—

In this feasibility trial, the TAXUS slow-release stent was well tolerated and showed promise for treatment of coronary lesions, with significant reductions in angiographic and intravascular ultrasound measures of restenosis.
The Crimes of the Flaneur
Authors: McDonough Tom
Published: January 2003

No matter what trail the flaneur may follow, every one of them will lead him to a crime. —Walter Benjamin, “The Paris of the Second Empire in Baudelaire”
Components of Switching Intentional Set
Authors: Rushworth Matthew F. S. , Passingham R. E. , Nobre A. C.
Published: January 2003

Despite the intuition that we can shift cognitive set on instruction, some behavioral studies have suggested that set shifting might only be accomplished once we engage in performance of the new task. It is possible that set switching consists of more than one component cognitive process and that the component processes might segregated in time. We recorded event-related potentials (ERPs) during two set-switching tasks to test whether different component processes were responsible for (i) set initiation and reconfiguration when presented with the instruction to switch, and (ii) the implementation of the new set once subjects engaged in performing the new task. The response switching (RS) task required shifts of intentional set; subjects selected between responses according to one of two conflicting intentional sets. The results demonstrated the existence of more than one constituent process. Some of the processes were linked to the initiation and reconfiguration of the set prior to actual performance of the new task. Other processes were time locked to performance of new task items. Set initiation started with modulation of medial frontal ERPs and was followed by modulation over parietal electrodes. Implementation of intentional set was associated with modulation of response-related ERPs.
Paradoxical Interhemispheric Summation in the Split Brain
Authors: Corballis Michael C. , Hamm Jeff P. , Barnett Kylie J. , Corballis Paul M.
Published: January 2003

We measured simple reaction time (RT) to light flashes, presented either singly or in pairs, in two people who had undergone callosotomy, one person with agenesis of the corpus callosum, and 17 normal subjects. The three split-brained subjects' RTs were decreased to bilateral pairs beyond predictions based on a simple race between independent unilateral processes, while those of the normal subjects were actually longer than predicted by the race model. This effect was present whether the bilateral pairs were in mirror-image locations or not, but was not present when the pairs were presented unilaterally. Since summation does not depend on close spatial correspondence, and also occurs when inputs are staggered in time, we suggest that it is due to cortical projection to a subcortical arousal system, and is normally inhibited by the corpus callosum.
Extensive Individual Differences in Brain Activations Associated with Episodic Retrieval are Reliable Over Time
Authors: Miller Michael B. , Van Horn John Darrell , Wolford George L. , Handy Todd C. , Valsangkar-Smyth Monica , Inati Souheil , Grafton Scott , Gazzaniga Michael S.
Published: January 2003

The localization of brain functions using neuroimaging techniques is commonly dependent on statistical analyses of groups of subjects in order to identify sites of activation, particularly in studies of episodic memory. Exclusive reliance on group analysis may be to the detriment of understanding the true underlying cognitive nature of brain activations. In the present study, we found that the patterns of brain activity associated with episodic retrieval are very distinct for individual subjects from the patterns of brain activity at the group level. These differences go beyond the relatively small variations due to cyctoarchitectonic differences or spatial normalization. We quantify this individual variability by cross-correlating volumes of brain images. We demonstrate that individual patterns of brain activity are reliable over time despite their extensive variability. We suggest that varied but reliable individual patterns of significant brain activity may be indicative of different cognitive strategies used to produce a recognition response. We believe that individual analysis in conjunction with group analysis may be critical to fully understanding the relationship between retrieval processes and underlying brain regions.