Zeno effect and switching of solitons in nonlinear couplers.

The Zeno effect is investigated for soliton type pulses in a nonlinear directional coupler with dissipation. The effect consists in increase of the coupler transparency with increase of the dissipative losses in one of the arms. It is shown that localized dissipation can lead to switching of solitons between the arms. Power losses accompanying the switching can be fully compensated by using a combination of dissipative and active (in particular, parity-time-symmetric) segments.

Matter waves in atomic-molecular condensates with Feshbach resonance management.

The dynamics of matter waves in the atomic to molecular condensate transition with a time-modulated atomic scattering length is investigated. Both the cases of rapid and slow modulations are studied. In the case of rapid modulations, the average over oscillations for the system is derived. The corresponding conditions for dynamical suppression of the association of atoms into the molecular field, or of second-harmonic generation in nonlinear optical systems, are obtained. For the case of slow modulations, we find resonant enhancement in the molecular field. We then illustrate chaos in the atomic-molecular BEC system. We suggest a sequential application of the two types of modulations, slow and rapid, when producing molecules.

Primary small intestinal neuroendocrine tumors are highly prevalent and often multiple before metastatic disease develops.

BACKGROUND: Small intestinal neuroendocrine tumors are the most common of small bowel malignancies with a clinical incidence of about 1 per 100,000 persons per year. There has been a threefold increase in the incidence of small intestinal neuroendocrine tumor during later decades, but there are no studies that clarify whether this is due to a true higher incidence or if the rise is a mere product of, for instance, improved diagnostic modalities. The aim of this study was to investigate the incidence of clinical as well as subclinical small intestinal neuroendocrine tumors found at autopsy as well as describing the frequency of concomitant malignancies in patients with small intestinal neuroendocrine tumor. MATERIALS AND METHODS: An autopsy registry from the Malmö county population from 1970 to 1982 with an 87% autopsy rate was used. The clinical autopsy reports for patients coded for the existence of "carcinoid tumor" were scrutinized for the presence of small intestinal neuroendocrine tumor, metastatic disease, and concomitant malignancies. Details of patients with clinically diagnosed small intestinal neuroendocrine tumor during this time period were gathered from the Swedish Cancer Registry. RESULTS: The mean annual incidence of small intestinal neuroendocrine tumor during this period was 5.33 per 100,000 individuals, and the mean annual prevalence was 581 per 100,000. The cause of death in the majority of cases was not due to small intestinal neuroendocrine tumor. In total, 48% of the people with small intestinal neuroendocrine tumor had at least one other malignancy, most commonly colorectal cancer. CONCLUSION: Most small intestinal neuroendocrine tumors are subclinical, and persons living with them will often die due to other causes. There was a high rate of multiple primary tumors (40%), suggesting that multiple tumors seem to arise before the advent of metastatic disease. Moreover, a comparably high rate of associated colorectal carcinoma was found.

Numerical simulations of NMR relaxation in chalk using local Robin boundary conditions.

The interpretation of nuclear magnetic resonance (NMR) data is of interest in a number of fields. In Ögren (2014) local boundary conditions for random walk simulations of NMR relaxation in digital domains were presented. Here, we have applied those boundary conditions to large, three-dimensional (3D) porous media samples. We compared the random walk results with known solutions and then applied them to highly structured 3D domains, from images derived using synchrotron radiation CT scanning of North Sea chalk samples. As expected, there were systematic errors caused by digitalization of the pore surfaces so we quantified those errors, and by using linear local boundary conditions, we were able to significantly improve the output. We also present a technique for treating numerical data prior to input into the ESPRIT algorithm for retrieving Laplace components of time series from NMR data (commonly called T-inversion).

Iatrogenic vascular injuries in Sweden. A nationwide study 1987-2005.

OBJECTIVES: To study the epidemiology of vascular injuries, with special focus on iatrogenic vascular injuries (IVIs) and time-trends. DESIGN AND METHODS: From the Swedish national vascular registry, Swedvasc, prospectively registered data on vascular injuries during 1987-2005 were analysed and cross-referenced for mortality against the population registry. RESULTS: Of 1853 injuries, 48% were caused by iatrogenic, 29% penetrating and 23% blunt trauma. In the three groups median age was 68, 35 and 40 years, respectively. The annual incidence of procedures for vascular injuries increased from 1.2-1.6 per 100 000 inhabitants and the proportion of IVIs increased from 41 to 51%, during the period. Mortality was higher after IVI (4.9%) compared to non-IVI (2.5%). Patients with IVI also had more co-morbidities; 58% cardiac disease, 44% hypertension, and 18% renal dysfunction. Among 888 IVIs, right femoral arterial injury was the most frequent (37%). The most common vascular reconstruction was direct suture (39%) followed by by-pass or interposition graft (19%, of which prosthetics were used in over half the cases). Endovascular repair increased from 4.6% to 15% between 1987 and 2005. CONCLUSIONS: Vascular injuries, in particular iatrogenic ones, appear to be increasing. Iatrogenic injuries affect vulnerable patients with co-morbidities and are associated with a high mortality.

Ankle brachial index combined with Framingham Risk Score to predict cardiovascular events and mortality: a meta-analysis.

CONTEXT: Prediction models to identify healthy individuals at high risk of cardiovascular disease have limited accuracy. A low ankle brachial index (ABI) is an indicator of atherosclerosis and has the potential to improve prediction. OBJECTIVE: To determine if the ABI provides information on the risk of cardiovascular events and mortality independently of the Framingham risk score (FRS) and can improve risk prediction. DATA SOURCES: Relevant studies were identified. A search of MEDLINE (1950 to February 2008) and EMBASE (1980 to February 2008) was conducted using common text words for the term ankle brachial index combined with text words and Medical Subject Headings to capture prospective cohort designs. Review of reference lists and conference proceedings, and correspondence with experts was conducted to identify additional published and unpublished studies. STUDY SELECTION: Studies were included if participants were derived from a general population, ABI was measured at baseline, and individuals were followed up to detect total and cardiovascular mortality. DATA EXTRACTION: Prespecified data on individuals in each selected study were extracted into a combined data set and an individual participant data meta-analysis was conducted on individuals who had no previous history of coronary heart disease. RESULTS: Sixteen population cohort studies fulfilling the inclusion criteria were included. During 480,325 person-years of follow-up of 24,955 men and 23,339 women, the risk of death by ABI had a reverse J-shaped distribution with a normal (low risk) ABI of 1.11 to 1.40. The 10-year cardiovascular mortality in men with a low ABI (< or = 0.90) was 18.7% (95% confidence interval [CI], 13.3%-24.1%) and with normal ABI (1.11-1.40) was 4.4% (95% CI, 3.2%-5.7%) (hazard ratio [HR], 4.2; 95% CI, 3.3-5.4). Corresponding mortalities in women were 12.6% (95% CI, 6.2%-19.0%) and 4.1% (95% CI, 2.2%-6.1%) (HR, 3.5; 95% CI, 2.4-5.1). The HRs remained elevated after adjusting for FRS (2.9 [95% CI, 2.3-3.7] for men vs 3.0 [95% CI, 2.0-4.4] for women). A low ABI (< or = 0.90) was associated with approximately twice the 10-year total mortality, cardiovascular mortality, and major coronary event rate compared with the overall rate in each FRS category. Inclusion of the ABI in cardiovascular risk stratification using the FRS would result in reclassification of the risk category and modification of treatment recommendations in approximately 19% of men and 36% of women. CONCLUSION: Measurement of the ABI may improve the accuracy of cardiovascular risk prediction beyond the FRS.

Quantum chaos and regularity in ultracold Fermi gases.

Quantum fluctuation of the energy is studied for an ultracold gas of interacting fermions trapped in a three-dimensional potential. Periodic-orbit theory is explored, and energy fluctuations are studied versus the particle number for generic regular and chaotic systems, as well as for a system defined by a harmonic confinement potential. Temperature effects on the energy fluctuations are investigated.

Dimensional reduction in Bose-Einstein condensed clouds of atoms confined in tight potentials of any geometry and any interaction strength.

Motivated by numerous experiments on Bose-Einstein condensed atoms which have been performed in tight trapping potentials of various geometries [elongated and/or toroidal (annular)], we develop a general method which allows us to reduce the corresponding three-dimensional Gross-Pitaevskii equation for the order parameter into an effectively one-dimensional equation, taking into account the interactions (i.e., treating the width of the transverse profile variationally) and the curvature of the trapping potential. As an application of our model we consider atoms which rotate in a toroidal trapping potential. We evaluate the state of lowest energy for a fixed value of the angular momentum within various approximations of the effectively one-dimensional model and compare our results with the full solution of the three-dimensional problem, thus getting evidence for the accuracy of our model.

Incidence and risk of venous thromboembolism in patients with verified arterial thrombosis: a population study based on 23,796 consecutive autopsies.

BACKGROUND: The relationship between atherothrombotic disease and venous thromboembolism (VTE) remains unclear. PATIENTS AND METHODS: In a cohort of 23,796 consecutive autopsies, performed using a standardized procedure and representing 84% of all in-hospital deaths between 1970 and 1982 in an urban Swedish population, we investigated the relationship between verified arterial thrombosis and VTE, with the hypothesis that patients with thrombosis in major artery segments have increased odds of VTE. RESULTS: We found an increased risk of VTE in patients with arterial thrombosis (Odds ratio; OR adjusted for gender and age 1.4, 95% confidence interval; CI 1.3-1.5) (P < 0.001). Patients with cervico-cranial and peripheral artery thrombosis had an excess risk even when controlling for age and major concomitant diseases. A negative association between coronary thrombosis and VTE in the univariate analysis (OR 0.7; 95% CI 0.6-0.8) (P < 0.001), was less pronounced in the multivariate analysis (OR 0.8; 95% CI 0.7-1.0) (P = 0.016). CONCLUSIONS: A positive association between atherothrombosis and VTE was confirmed, except in patients with coronary thrombosis, where IHD as competing death cause is a possible confounder. Our findings indicate a potential for directed prevention, but may also imply similarities in etiology.

Reduced cardiovascular mortality risk in male smokers who are physically active. Results from a 25-year follow-up of the prospective population study men born in 1914.

OBJECTIVE: To assess to what extent physical activity during leisure time may modify the mortality risk associated with smoking. METHODS: Population-based cohort study in the city of Malmö, Sweden. The 642 men included in this study were all born in 1914 and were all free of cardiovascular disease at the baseline examination in 1968 and 1969. Smoking habits and physical activity during leisure time were assessed by a structured questionnaire. Main outcome measures were total and cardiovascular mortality rates during 25 years of follow-up. RESULTS: The total and cardiovascular mortality rates in smokers were 33.2 per 1000 person-years and 15.9 per 1000 person-years, respectively. Corresponding figures in nonsmokers were 17.8 per 1000 person-years and 7.5 per 1000 person-years. Mortality rates in smokers were strongly related to daily tobacco consumption. Physically active men had lower overall (adjusted relative risk [RR], 0.7; 95% confidence interval [CI], 0.5-0.9) and cardiovascular (adjusted RR, 0.6; 95% CI, 0.3-0.9) mortality rates than sedentary men. Physically active men who never smoked (used as the control category) had the lowest death rate, and physically inactive smokers the highest (adjusted RR, 3.6; 95% CI, 2.1-6.3). The cardiovascular death rates in these 2 groups were 4.3 per 1000 person-years and 16.6 per 1000 person-years, respectively (adjusted RR, 5.5; 95% CI, 2.2-13.6). Vigorous physical activity in smokers was associated with an almost 40% lower cardiovascular mortality rate (RR, 0.6; 95% CI, 0.3-1.2; P = .11). CONCLUSIONS: Regular physical activity was associated with lower total and cardiovascular mortality rates. Similar effects were observed in both nonsmokers and smokers.

COBRA: A prospective multimodal imaging study of dopamine, brain structure and function, and cognition.

Cognitive decline is a characteristic feature of normal human aging. Previous work has demonstrated marked interindividual variability in onset and rate of decline. Such variability has been linked to factors such as maintenance of functional and structural brain integrity, genetics, and lifestyle. Still, few, if any, studies have combined a longitudinal design with repeated multimodal imaging and a comprehensive assessment of cognition as well as genetic and lifestyle factors. The present paper introduces the Cognition, Brain, and Aging (COBRA) study, in which cognitive performance and brain structure and function are measured in a cohort of 181 older adults aged 64 to 68 years at baseline. Participants will be followed longitudinally over a 10-year period, resulting in a total of three equally spaced measurement occasions. The measurement protocol at each occasion comprises a comprehensive set of behavioral and imaging measures. Cognitive performance is evaluated via computerized testing of working memory, episodic memory, perceptual speed, motor speed, implicit sequence learning, and vocabulary. Brain imaging is performed using positron emission tomography with [(11)C]-raclopride to assess dopamine D2/D3 receptor availability. Structural magnetic resonance imaging (MRI) is used for assessment of white and gray-matter integrity and cerebrovascular perfusion, and functional MRI maps brain activation during rest and active task conditions. Lifestyle descriptives are collected, and blood samples are obtained and stored for future evaluation. Here, we present selected results from the baseline assessment along with a discussion of sample characteristics and methodological considerations that determined the design of the study. This article is part of a Special Issue entitled SI: Memory & Aging.

The structural organization of the inferior and lateral subdivisions of the Macaca monkey pulvinar.

Previous light microscopic studies of Macaca pulvinar have demonstrated that both the inferior and adjacent portion of the lateral pulvinar subdivisions are reciprocally connected to the entire occipital lobe, including striate cortex. They differ in that inferior but not lateral pulvinar receives a projection from the superficial layers of the superior colliculus. In this study, the internal organization of these two subdivisions in compared by relating light microscopic Golgi morphology to the synaptic organization observed by electron microscopy. The Golgi impregnated neurons in inferior and lateral pulvinar are typical of other thalamic nuclei and are not qualitatively different in the two subdivisions. Projections neurons (PN) vary in cell body (15--40 micrometers) and dendritic tree (150--600 micrometers) diameters but bear the same varieties of dendritic appendages; spine-like, hair-like, and knot-like. Local circuit neurons (LCN) have smaller cell body diameters (10--20 micrometers) but can have very large dendritic field diameters (150--600 micrometers). They are best distinguished from PNs by their elaborate dendritic appendages, which have been identified as pre-synaptic dendrites in the EM. LCN axons are infrequently seen. In the EM both subdivisions contain four types of synaptic terminals. RS and RL terminal both contain round symaptic vesicles and make asymmetric synaptic contacts, but are subdivided on the basis of small (RS = 0.09 micrometers) versus large (RL = 2.2 micrometers) cross sectional diameters and organelle content. RLs contact larger caliber dendrites and frequently form synaptic complexes with presynaptic dendrites of LCNs, while RSs contact fine caliber dendrites and rarely take part in synaptic complexes. F terminal and P boutons both contain flat and pleomorphis vesicles and make symmetric synaptic contacts. They are characterized by vesicle number and cytoplasmic density. Fs are infrequently observed in pulvinar compared to P boutons and are of uncertain origin. P boutons can be equated with LCN dendritic appendages and have been identified as pre-synaptic dendrites. The quantitative distribution of each type is very similar in both subdivisions, avveraging RS 85%, RL 5%, F 0.3%, P 8% and unidentified 2%.

The morphology and distribution of striate cortex terminals in the inferior and lateral subdivisions of the Macaca monkey pulvinar.

The origin of the various types of axon terminals in Macaca pulvinar remains uncertain because of the contradictory results obtained in EM degeneration studies. We have used EM-autoradiography to determine the morphology of terminals in the inferior and lateral pulvinar which originate from neurons in visual cortex. After injections of H3 proline into area 17, both the small diameter (RS) and the large diameter (RL) terminals containing round vesicles and making asymmetric contacts are labeled in the two pulvinar subdivisions. Labeled and unlabeled terminals are intermixed within the pulvinar focus which suggests that the dendrites of the same pulvinar neuron receive overlapping inputs from several cortical areas. Because only 5% of the pulvinar terminals are RLs (Ogren and Hendrickson, '79), and this small number of RLs originates from at least two visual cortical areas plus the superior colliculus (Partlow et al., '77), superior colliculus input to inferior pulvinar is small compared to the combined RS and RL cortical input. Together the findings from this study and the preceding paper (Ogren and Henderickson, '79), show that while pulvinar is typical of other thalamic nuclei in the structure of its neurons and synapses, it differs in that the input from subcortical structures is minimal. It is suggested that inferior and lateral pulvinar function principally as integrators of visula cortical information.

The neuroanatomical organization of pathways between the dorsal lateral geniculate nucleus and visual cortex in Old World and New World primates.

Pathways between the dorsal lateral geniculate nucleus (dLGN) and visual cortex in Old World (Macaca, Papio, Erythrocebus, Cercopithecus) and New World (Saimiri, Cebus) primates were studied after injections of horseradish peroxidase and H3 or S35 amino acids into the dLGN or visual cortex. Trans-synaptic autoradiography was also used to study these pathways after an injection of H3 proline-fucose into one eye. The subsequent autoradiographs of visual cortex showed that Old World primates have separate eye inputs (ocular dominance columns) in the striate cortex, whereas New World monkeys have overlapping or non-separated eye inputs. In both primate groups the geniculocortical input to layer IVA formed a pattern which resembled a honeycomb in tangential sections, unlike the solidly labeled layer IVC. Also common to the two primate groups was a projection from dLGN to layer VI. There was no dLGN projection to any prestriate area in any of the primates. However, after an injection limited to the prestriate cortex of Macaca, light autoradiographic labeling was seen in the interlaminar zones and the magnocellular and S laminae, demonstrating a prestriate-dLGN pathway. Our results indicate that the primate visual system differs significantly from the cat in having no dLGN projection to area 18. There are also signficant differences between primates in the level at which the possibility of binocularity (of an excitatory nature) first occurs in the striate cortex because in the species studied thus far with neuroanatomical methods, Old World primates have ocular dominance columns in layer IV but most New World monkeys lack them.

Anatomical organization of primate visual cortex area VII.

The Golgi Rapid and Kopsch techniques have been used to provide material for an examination of the internal neuronal organization of cortical area VII of the Macaca monkey. The afferent and efferent relationships of area VII, as shown by axoplasmic transport tracing techniques in our own material and in previous studies in other laboratories, are reviewed. Comparison is made between the internal organisation of VI and VII cortex in terms of (1) the marked different in spiny and nonspiny neurons populations of granular layer 4, (2) the difference in relationship of lamina 6 pyramidal neurons to the overlying layers with a shift away from any relationship to granular layer 4 in VII, and (3) differences in the organization of VI lamina 4B and VII lamina 3B--both similarly placed, fiber-rich bands in the two cortical areas. The extrinsic relationships of VI and VII with the lateral geniculate nucleus, superior colliculus, pulvinar, peristriate cortex, cortical area STS, and with each other are compared in terms of laminar locations of efferent neurons and afferent axon terminal fields. It is hoped that this anatomical survey will provide a better foundation for physiological explorations of the region.

Alterations in visually related eye movements following left pulvinar damage in man.

This case study presents evidence for two subtle types of eye movement abnormalities following surgical resection of the left posterior pulvinar in man. First, visual fixations during vertical pattern matching are on average both increased in number and prolonged in duration compared to controls, although normal fixation durations also occur. Second, unilateral deficiencies during search and scanning performance are associated with eye movements directed into the hemifield contralateral to the lesion. Although direct damage to parietal cortex and indirect damage to other visually related structures cannot be ruled out as other explanations for these deficits, these findings are consistent with recent electrophysiological and behavioral studies of the pulvinar in both human and non-human primates, and suggests a fruitful area for further investigation of pulvinar function.

Plethysmographic pulse wave amplitude and future leg arteriosclerosis.

A low pulse wave amplitude during calf plethysmography at 55 years of age was previously found to be associated with an increased mortality and incidence of myocardial infarction. In order to test the hypothesis that a low pulse wave amplitude is associated with an increased risk of future leg atherosclerosis as well, we have studied the relationship between a low ankle-brachial pressure index (ABPI; < 0.9) at 68 years of age and the pulse wave amplitude at 55 years of age in that same cohort. The prevalence of a low pulse wave amplitude (< or = 5 mm; lowest quintile) among men with a low ABPI (42%) was more than twice as high as it was among men who had a normal ABPI (19%) (P < 0.001). No association was found between a low ABPI and the plethysmographically recorded leg blood flow at 55 years of age. A low pulse wave amplitude might reflect early symptom-free arteriosclerosis, or age-dependent non-arteriosclerotic loss of vessel wall elasticity. The relationship between a low pulse wave amplitude and a low ABPI remained when controlling for smoking, hypertension and hyperlipidaemia. It is concluded that pulse wave measurement by plethysmography contributes information to improve leg atherosclerotic risk assessment in individuals exposed to known risk factors.

Receptor imaging technique with 11C-labeled receptor ligands in living brain slices: its application to time-resolved imaging and saturation analysis of benzodiazepine receptor using [11C]Ro15-1788.

Recently we developed a novel imaging technique using positron emitter-labeled compounds as probes and a storage phosphor screen as a detector. This approach makes it possible to follow a variety of biochemical processes with spatial information in living brain slices. Further technical development is reported here in terms of time-resolved imaging and receptor characterization in a real equilibrium state. The method was validated by use of [11C]Ro15-1788, a benzodiazepine receptor antagonist. Fresh brain slices were incubated with [11C]Ro15-1788 in oxygenated Krebs-Ringer solution at 37 degrees C, in a specially designed chamber. By placing the chamber on a storage phosphor screen, we could obtain two-dimensional images of radioactivity in the slices. Time-resolved imaging was made at 5 min intervals, revealing that it took 60 min to reach equilibrium binding. The dissociation process was observed by adding an excess amount of unlabeled Ro15-1788 to the chamber, 25 min was required for the full dissociation. In the equilibrium state, i.e. in the presence of free radio-ligand, Scatchard plot analysis was performed on the cerebral cortex (Kd = 7.4 nM, Bmax = 146 fmol/mg tissue) and striatum (Kd = 7.5 nM, Bmax = 107 fmol/mg tissue), suggesting the presence of a single component of binding site in these two regions. The present method, for the first time, made it possible to study a ligand-receptor interaction in living brain slices with temporal and spatial resolutions. This technique should prove useful for studies of receptor function under physiological conditions.

In vivo positron emission tomography studies on the novel nicotinic receptor agonist [11C]MPA compared with [11C]ABT-418 and (S)(-)[11C]nicotine in rhesus monkeys.

The novel 11C-labeled nicotinic agonist (R,S)-1-[11C]methyl-2(3-pyridyl)azetidine ([11C]MPA) was evaluated as a positron emission tomography (PET) ligand for in vivo characterization of nicotinic acetylcholine receptors in the brain of Rhesus monkeys in comparison with the nicotinic ligands (S)-3-methyl-5-(1-[11C]methyl-2-pyrrolidinyl)isoxazol ([11C]ABT-418) and (S)(-)[11C]nicotine. The nicotinic receptor agonist [11C]MPA demonstrated rapid uptake into the brain to a similar extent as (S)(-) [11C]nicotine and [11C]ABT-418. When unlabeled (S)(-)nicotine (0.02 mg/kg) was administered 5 min before the radioactive tracers, the uptake of [11C]MPA was decreased by 25% in the thalamus, 19% in the temporal cortex, and 11% in the cerebellum, whereas an increase was found for the uptake of (S)(-)[11C]nicotine and [11C]ABT-418. This finding indicates specific binding of [11C]MPA to nicotinic receptors in the brain in a simple classical displacement study. [11C]MPA seems to be a more promising radiotracer than (S)(-)[11C]nicotine or [11C]ABT-418 for PET studies to characterize nicotinic receptors in the brain.

Methodological aspects for in vitro characterization of receptor binding using 11C-labeled receptor ligands: a detailed study with the benzodiazepine receptor antagonist [11C]Ro 15-1788.

As a complement to in vivo studies with positron emission tomography (PET), it is desirable to perform in vitro characterization of newly developed 11C tracers. In this report we describe the technique for determination of receptor-ligand kinetics utilizing ligands labeled with the short-lived radionuclide 11C. The limitations and advantages are discussed. The benzodiazepine antagonist [11C]Ro 15-1788 was used as a model substance, and the use of storage phosphor plates for quantification of radioactivity was validated. Storage phosphor plates showed an excellent linear range (approximately 10[3]) and acceptable resolution (approximately 0.5 mm). Receptor-ligand kinetics, including depletion, association and dissociation, saturation and displacement were evaluated with good results through the use of short-lived radiotracers and storage phosphor plates.