Showing papers by "Radboud University Nijmegen published in 2005"

Two-dimensional gas of massless Dirac fermions in graphene

Abstract: Quantum electrodynamics (resulting from the merger of quantum mechanics and relativity theory) has provided a clear understanding of phenomena ranging from particle physics to cosmology and from astrophysics to quantum chemistry. The ideas underlying quantum electrodynamics also influence the theory of condensed matter, but quantum relativistic effects are usually minute in the known experimental systems that can be described accurately by the non-relativistic Schrodinger equation. Here we report an experimental study of a condensed-matter system (graphene, a single atomic layer of carbon) in which electron transport is essentially governed by Dirac's (relativistic) equation. The charge carriers in graphene mimic relativistic particles with zero rest mass and have an effective 'speed of light' c* approximately 10(6) m s(-1). Our study reveals a variety of unusual phenomena that are characteristic of two-dimensional Dirac fermions. In particular we have observed the following: first, graphene's conductivity never falls below a minimum value corresponding to the quantum unit of conductance, even when concentrations of charge carriers tend to zero; second, the integer quantum Hall effect in graphene is anomalous in that it occurs at half-integer filling factors; and third, the cyclotron mass m(c) of massless carriers in graphene is described by E = m(c)c*2. This two-dimensional system is not only interesting in itself but also allows access to the subtle and rich physics of quantum electrodynamics in a bench-top experiment.

The 2005 International Society of Urological Pathology (ISUP) consensus conference on Gleason grading of prostatic carcinoma

Abstract: Five years after the last prostatic carcinoma grading consensus conference of the International Society of Urological Pathology (ISUP), accrual of new data and modification of clinical practice require an update of current pathologic grading guidelines. This manuscript summarizes the proceedings of the ISUP consensus meeting for grading of prostatic carcinoma held in September 2019, in Nice, France. Topics brought to consensus included the following: (1) approaches to reporting of Gleason patterns 4 and 5 quantities, and minor/tertiary patterns, (2) an agreement to report the presence of invasive cribriform carcinoma, (3) an agreement to incorporate intraductal carcinoma into grading, and (4) individual versus aggregate grading of systematic and multiparametric magnetic resonance imaging-targeted biopsies. Finally, developments in the field of artificial intelligence in the grading of prostatic carcinoma and future research perspectives were discussed.

Self-Assembled Nanoreactors

Abstract: An overview of the wide range of nanoreactors that have been constructed from synthetic and biological building blocks using both covalent and noncovalent approaches is given. Focus is on self-assembled systems, varying in size from a few nanometers to tens of micrometers. The review is divided into several sections that cover the development of tailor-made nanoreactors, starting from small organic molecular containers expanding to large compartment-containing assemblies. First, the construction of capsules from low molecular weight compounds by means of covalent synthesis and self-assembly by highly directive and pre-designed interactions is discussed. Second, nanocapsules based on micellar and vesicular assemblies that are built up frow low molecular weight molecules are described. Finally, the construction of nanoreactors from macromolecular building blocks, as well as recent developments in the use of viruses as nanocontainers and reactors are outlined.

Substitution of doctors by nurses in primary care

Abstract: Background Demand for primary care services has increased in developed countries due to population ageing, rising patient expectations, and reforms that shift care from hospitals to the community. At the same time, the supply of physicians is constrained and there is increasing pressure to contain costs. Shifting care from physicians to nurses is one possible response to these challenges. The expectation is that nurse-doctor substitution will reduce cost and physician workload while maintaining quality of care. Objectives Our aim was to evaluate the impact of doctor-nurse substitution in primary care on patient outcomes, process of care, and resource utilisation including cost. Patient outcomes included: morbidity; mortality; satisfaction; compliance; and preference. Process of care outcomes included: practitioner adherence to clinical guidelines; standards or quality of care; and practitioner health care activity (e.g. provision of advice). Resource utilisation was assessed by: frequency and length of consultations; return visits; prescriptions; tests and investigations; referral to other services; and direct or indirect costs. Search methods The following databases were searched for the period 1966 to 2002: Medline; Cinahl; Bids, Embase; Social Science Citation Index; British Nursing Index; HMIC; EPOC Register; and Cochrane Controlled Trial Register. Search terms specified the setting (primary care), professional (nurse), study design (randomised controlled trial, controlled before-and-after-study, interrupted time series), and subject (e.g. skill mix). The searches for this review were conducted in 2002 and are now out-of-date and therefore the review findings should be used with caution. The review is currently being updated and the updated version should be published before the end of 2014. Selection criteria Studies were included if nurses were compared to doctors providing a similar primary health care service (excluding accident and emergency services). Primary care doctors included: general practitioners, family physicians, paediatricians, general internists or geriatricians. Primary care nurses included: practice nurses, nurse practitioners, clinical nurse specialists, or advanced practice nurses. Data collection and analysis Study selection and data extraction was conducted independently by two reviewers with differences resolved through discussion. Meta-analysis was applied to outcomes for which there was adequate reporting of intervention effects from at least three randomised controlled trials. Semi-quantitative methods were used to synthesize other outcomes. Main results 4253 articles were screened of which 25 articles, relating to 16 studies, met our inclusion criteria. In seven studies the nurse assumed responsibility for first contact and ongoing care for all presenting patients. The outcomes investigated varied across studies so limiting the opportunity for data synthesis. In general, no appreciable differences were found between doctors and nurses in health outcomes for patients, process of care, resource utilisation or cost. In five studies the nurse assumed responsibility for first contact care for patients wanting urgent consultations during office hours or out-of-hours. Patient health outcomes were similar for nurses and doctors but patient satisfaction was higher with nurse-led care. Nurses tended to provide longer consultations, give more information to patients and recall patients more frequently than did doctors. The impact on physician workload and direct cost of care was variable. In four studies the nurse took responsibility for the ongoing management of patients with particular chronic conditions. The outcomes investigated varied across studies so limiting the opportunity for data synthesis. In general, no appreciable differences were found between doctors and nurses in health outcomes for patients, process of care, resource utilisation or cost. Authors' conclusions The findings suggest that appropriately trained nurses can produce as high quality care as primary care doctors and achieve as good health outcomes for patients. However, this conclusion should be viewed with caution given that only one study was powered to assess equivalence of care, many studies had methodological limitations, and patient follow-up was generally 12 months or less. While doctor-nurse substitution has the potential to reduce doctors' workload and direct healthcare costs, achieving such reductions depends on the particular context of care. Doctors' workload may remain unchanged either because nurses are deployed to meet previously unmet patient need or because nurses generate demand for care where previously there was none. Savings in cost depend on the magnitude of the salary differential between doctors and nurses, and may be offset by the lower productivity of nurses compared to doctors.

Effectiveness and efficiency of guideline dissemination and implementation strategies

Abstract: Objectives: A systematic review of the effectiveness and costs of different guideline development, dissemination, and implementation strategies wasundertaken. The resource implications of these strategies was estimated, and a framework for deciding when it is efficient to develop and introduce clinical guidelines was developed.

A molecular phylogeny for bats illuminates biogeography and the fossil record.

Abstract: Bats make up more than 20% of extant mammals, yet their evolutionary history is largely unknown because of a limited fossil record and conflicting or incomplete phylogenies. Here, we present a highly resolved molecular phylogeny for all extant bat families. Our results support the hypothesis that megabats are nested among four major microbat lineages, which originated in the early Eocene [52 to 50 million years ago (Mya)], coincident with a significant global rise in temperature, increase in plant diversity and abundance, and the zenith of Tertiary insect diversity. Our data suggest that bats originated in Laurasia, possibly in North America, and that three of the major microbat lineages are Laurasian in origin, whereas the fourth is Gondwanan. Combining principles of ghost lineage analysis with molecular divergence dates, we estimate that the bat fossil record underestimates (unrepresented basal branch length, UBBL) first occurrences by, on average, 73% and that the sum of missing fossil history is 61%.

Ultrafast non-thermal control of magnetization by instantaneous photomagnetic pulses.

Abstract: The demand for ever-increasing density of information storage and speed of manipulation has triggered an intense search for ways to control the magnetization of a medium by means other than magnetic fields. Recent experiments on laser-induced demagnetization and spin reorientation use ultrafast lasers as a means to manipulate magnetization, accessing timescales of a picosecond or less. However, in all these cases the observed magnetic excitation is the result of optical absorption followed by a rapid temperature increase. This thermal origin of spin excitation considerably limits potential applications because the repetition frequency is limited by the cooling time. Here we demonstrate that circularly polarized femtosecond laser pulses can be used to non-thermally excite and coherently control the spin dynamics in magnets by way of the inverse Faraday effect. Such a photomagnetic interaction is instantaneous and is limited in time by the pulse width (approximately 200 fs in our experiment). Our finding thus reveals an alternative mechanism of ultrafast coherent spin control, and offers prospects for applications of ultrafast lasers in magnetic devices.

Cardiovascular pre-participation screening of young competitive athletes for prevention of sudden death: proposal for a common European protocol Consensus Statement of the Study Group of Sport Cardiology of the Working Group of Cardiac Rehabilitation and Exercise Physiology and the Working Group of Myocardial and Pericardial Diseases of the European Society of Cardiology

Abstract: The 1996 American Heart Association consensus panel recommendations stated that pre-participation cardiovascular screening for young competitive athletes is justifiable and compelling on ethical, legal, and medical grounds. The present article represents the consensus statement of the Study Group on Sports Cardiology of the Working Group on Cardiac Rehabilitation and Exercise Physiology and the Working Group on Myocardial and Pericardial diseases of the European Society of Cardiology, which comprises cardiovascular specialists and other physicians from different European countries with extensive clinical experience with young competitive athletes, as well as with pathological substrates of sudden death. The document takes note of the 25-year Italian experience on systematic pre-participation screening of competitive athletes and focuses on relevant issues, mostly regarding the relative risk, causes, and prevalence of sudden death in athletes; the efficacy, feasibility, and cost-effectiveness of population-based pre-participation cardiovascular screening; the key role of 12-lead ECG for identification of cardiovascular diseases such as cardiomyopathies and channelopathies at risk of sudden death during sports; and the potential of preventing fatal events. The main purpose of the consensus document is to reinforce the principle of the need for pre-participation medical clearance of all young athletes involved in organized sports programmes, on the basis of (i) the proven efficacy of systematic screening by 12-lead ECG (in addition to history and physical examination) to identify hypertrophic cardiomyopathy-the leading cause of sports-related sudden death-and to prevent athletic field fatalities; (ii) the potential screening ability in detecting other lethal cardiovascular diseases presenting with ECG abnormalities. The consensus document recommends the implementation of a common European screening protocol essentially based on 12-lead ECG.

Methicillin-resistant Staphylococcus aureus in pig farming.

Abstract: We conducted a study among a group of 26 regional pig farmers to determine the methicillin-resistant Staphylococcus aureus prevalence rate and found it was >760 times greater than the rate of patients admitted to Dutch hospitals. While spa-type t108 is apparently a more widespread clone among pig farmers and their environment, we did find other spa-types.

Magnetic resonance tracking of dendritic cells in melanoma patients for monitoring of cellular therapy

Abstract: The success of cellular therapies will depend in part on accurate delivery of cells to target organs. In dendritic cell therapy, in particular, delivery and subsequent migration of cells to regional lymph nodes is essential for effective stimulation of the immune system. We show here that in vivo magnetic resonance tracking of magnetically labeled cells is feasible in humans for detecting very low numbers of dendritic cells in conjunction with detailed anatomical information. Autologous dendritic cells were labeled with a clinical superparamagnetic iron oxide formulation or (111)In-oxine and were co-injected intranodally in melanoma patients under ultrasound guidance. In contrast to scintigraphic imaging, magnetic resonance imaging (MRI) allowed assessment of the accuracy of dendritic cell delivery and of inter- and intra-nodal cell migration patterns. MRI cell tracking using iron oxides appears clinically safe and well suited to monitor cellular therapy in humans.

An overview of JML tools and applications

Abstract: The Java Modeling Language (JML) can be used to specify the detailed design of Java classes and interfaces by adding annotations to Java source files. The aim of JML is to provide a specification language that is easy to use for Java programmers and that is supported by a wide range of tools for specification typechecking, runtime debugging, static analysis, and verification.This paper gives an overview of the main ideas behind JML, details about JML’s wide range of tools, and a glimpse into existing applications of JML.

International migration, remittances and development: myths and facts

Abstract: The debate on international South-North labour migration tends to focus on the receiving end of migration. This bias obscures a proper understanding of the developmental causes and consequences of migration at the sending end. The reciprocal migration - development relationship is examined through the discussion of seven migration 'myths'. Because of its profound developmental roots, it is useless to think that migration can be halted or that aid and trade are short-cut 'solutions' to immigration. Migrant remittances contribute significantly to development and living conditions in sending countries. Nevertheless, the recent 'remittance euphoria' is not justified, because unattractive investment environments and restrictive immigration policies which interrupt circular migration patterns prevent the high development potential of migration from being fully realised. Although specific policies can enhance this potential through facilitating remittance transfers and investments, the key lies in encouraging circular migration. Instead of uselessly and harmfully trying to stop inevitable migration, immigration policies allowing for freer circulation can, besides increasing migration control, enhance the vital contribution of migrants to the development of their home countries.

Trust, Contract and Relationship Development

Abstract: This article contributes to the debate on the relation between trust and control in the management of inter-organizational relations. More specifically, we focus on the question how trust and formal contract are related. While there have been studies on whether trust and contract are substitutes or complements, they offer little insight into the dynamic interaction between the two. They fail to answer, first, whether contract precedes trust or follows it, in other words, what causal relationship exists between the concepts; second, how and why trust and contract can substitute or complement each other; and third, how the various combinations of trust and contract affect a relationship’s development and outcome. In search of answers, we conducted longitudinal case studies to reveal the relationship between trust, contract and relationship outcome in complex inter-firm relationships. We find trust and contract to be both complements and substitutes and find that a close study of a contract’s content offers alternative insight into the presence and use of contracts in inter-firm relationships.

Prognostic Value of Histologic Subtypes in Renal Cell Carcinoma: A Multicenter Experience

Abstract: Purpose To analyze to what extent histologic subtype is of prognostic importance in renal cell carcinoma based on a large, international, multicenter experience. Patients and Methods Four thousand sixty-three patients from eight international centers were included in this retrospective study. Histologic subtype (1997 International Union Against Cancer [UICC] criteria of tumor response), age, sex, TNM stage, Fuhrman grade, tumor size, Eastern Cooperative Oncology Goup performance status (ECOG PS), and overall survival were determined in all cases. The prognostic values of clear cell, papillary, and chromophobe histologic features were assessed by uni- and multivariate analysis using the Kaplan-Meier method and Cox model, respectively. Results Clear cell, papillary, and chromophobe carcinomas accounted for 3,564 (87.7%), 396 (9.7%) and 103 (2.5%) cases, respectively. In univariate analysis, a trend toward a better survival was observed when clear cell, papillary, and chromophobe histologies were considered ...

Dynamical singlets and correlation-assisted Peierls transition in VO2

Abstract: A theory of the metal-insulator transition in vanadium dioxide from the high- temperature rutile to the low- temperature monoclinic phase is proposed on the basis of cluster dynamical mean-field theory, in conjunction with the density functional scheme. The interplay of strong electronic Coulomb interactions and structural distortions, in particular, the dimerization of vanadium atoms in the low-temperature phase, plays a crucial role. We find that ${\mathrm{V}\mathrm{O}}_{2}$ is not a conventional Mott insulator, but that the formation of dynamical V-V singlet pairs due to strong Coulomb correlations is necessary to trigger the opening of a Peierls gap.

The conceptualization and measurement of burnout: Common ground and worlds apart

Abstract: In this edition of Work & Stress, Kristensen and his colleagues critically discuss the Maslach Burnout Inventory (MBI) and present an alternative, more general instrument to measure burnout that exclusively focuses on exhaustion. Here we critically examine their reasons for developing a new burnout measure, as well as the theoretical foundations of this measure. Whereas we agree with Kristensen et al.'s remarks concerning the availability and item wording of the MBI, we do not share their concerns regarding its theoretical underpinnings. In our view, burnout should be conceptualized as a primarily work-related syndrome of (at least) exhaustion and depersonalization/cynicism. The MBI would seem to fit that conceptualization very well.

Neuronal coherence as a mechanism of effective corticospinal interaction

Abstract: Neuronal groups can interact with each other even if they are widely separated. One group might modulate its firing rate or its internal oscillatory synchronization to influence another group. We propose that coherence between two neuronal groups is a mechanism of efficient interaction, because it renders mutual input optimally timed and thereby maximally effective. Modulations of subjects' readiness to respond in a simple reaction-time task were closely correlated with the strength of gamma-band (40 to 70 hertz) coherence between motor cortex and spinal cord neurons. This coherence may contribute to an effective corticospinal interaction and shortened reaction times.

Work-home interaction from a work psychological perspective: Development and validation of a new questionnaire, the SWING

Abstract: This paper reports on the stepwise development of a new questionnaire for measuring work-home interaction, i.e. the Survey Work-home Interaction—NijmeGen, the SWING). Inspired by insights from work psychology, more specifically from Effort-Recovery Theory (Meijman & Mulder, 1998), we defined work-home interaction by differentiating between the direction and quality of influence. Four types of work-home interaction were distinguished and measured by using 22 (including 13 self-developed) items. By using data from five independent samples (total N=2472), validity evidence was provided based on the internal structure of the questionnaire. The results showed that the questionnaire reliably measured four empirically distinct types of work-home interaction, and that this four-dimensional structure was largely invariant across the five samples as well as across relevant subgroups. Validity evidence was also provided based on the relations with external (theoretically relevant) variables (i.e. job charac...

Foundations of attack trees

Abstract: Attack trees have found their way to practice because they have proved to be an intuitive aid in threat analysis. Despite, or perhaps thanks to, their apparent simplicity, they have not yet been provided with an unambiguous semantics. We argue that such a formal interpretation is indispensable to precisely understand how attack trees can be manipulated during construction and analysis. We provide a denotational semantics, based on a mapping to attack suites, which abstracts from the internal structure of an attack tree, we study transformations between attack trees, and we study the attribution and projection of an attack tree.

Continuous-time quantum Monte Carlo method for fermions

Abstract: We present a numerically exact continuous-time quantum Monte Carlo algorithm for fermions with a general interaction nonlocal in space-time The new determinantal grand-canonical scheme is based on a stochastic series expansion for the partition function in the interaction representation The method is particularly applicable for multiband, time-dependent correlations since it does not invoke the Hubbard-Stratonovich transformation The test calculations for exactly solvable models, as well results for the Green function and for the time-dependent susceptibility of the multiband supersymmetric model with a spin-flip interaction are discussed

The INT Photometric Hα Survey of the Northern Galactic Plane (IPHAS)

Abstract: The Isaac Newton Telescope (INT) Photometric Halpha Survey of the Northern Galactic Plane (IPHAS) is a 1800-deg 2 CCD survey of the northern Milky Way spanning the latitude range -5° < b < + 5° and reaching down to r'~= 20 (10sigma). Representative observations and an assessment of point-source data from IPHAS, now underway, are presented. The data obtained are Wide Field Camera images in the Halpha narrow-band, and Sloan r' and i' broad-band filters. We simulate IPHAS (r'-Halpha,r'-i') point-source colours using a spectrophotometric library of stellar spectra and available filter transmission profiles: this defines the expected colour properties of (i) solar metallicity stars, without Halpha emission, and (ii) emission-line stars. Comparisons with observations of fields in Aquila show that the simulations of normal star colours reproduce the observations well for all spectral types earlier than M. A further comparison between colours synthesized from long-slit flux-calibrated spectra and IPHAS photometry for six objects in a Taurus field confirms the reliability of the pipeline calibration. Spectroscopic follow-up of a field in Cepheus shows that sources lying above the main stellar locus in the (r'- Halpha,r'-i') plane are confirmed to be emission-line objects with very few failures. In this same field, examples of Halpha deficit objects (a white dwarf and a carbon star) are shown to be readily distinguished by their IPHAS colours. The role IPHAS can play in studies of spatially resolved northern Galactic nebulae is discussed briefly and illustrated by a continuum-subtracted mosaic image of Shajn 147 (a supernova remnant, 3° in diameter). The final catalogue of IPHAS point sources will contain photometry on about 80 million objects. Used on its own, or in combination with near-infrared photometric catalogues, IPHAS is a major resource for the study of stellar populations making up the disc of the Milky Way. The eventual yield of new northern emission-line objects from IPHAS is likely to be an order of magnitude increase on the number already known.

GJB2 mutations and degree of hearing loss: a multicenter study.

Abstract: Hearing impairment (HI) affects 1 in 650 newborns, which makes it the most common congenital sensory impairment. Despite extraordinary genetic heterogeneity, mutations in one gene, GJB2, which encodes the connexin 26 protein and is involved in inner ear homeostasis, are found in up to 50% of patients with autosomal recessive nonsyndromic hearing loss. Because of the high frequency of GJB2 mutations, mutation analysis of this gene is widely available as a diagnostic test. In this study, we assessed the association between genotype and degree of hearing loss in persons with HI and biallelic GJB2 mutations. We performed cross-sectional analyses of GJB2 genotype and audiometric data from 1,531 persons, from 16 different countries, with autosomal recessive, mild-to-profound nonsyndromic HI. The median age of all participants was 8 years; 90% of persons were within the age range of 0-26 years. Of the 83 different mutations identified, 47 were classified as nontruncating, and 36 as truncating. A total of 153 different genotypes were found, of which 56 were homozygous truncating (T/T), 30 were homozygous nontruncating (NT/NT), and 67 were compound heterozygous truncating/nontruncating (T/NT). The degree of HI associated with biallelic truncating mutations was significantly more severe than the HI associated with biallelic nontruncating mutations (P<.0001). The HI of 48 different genotypes was less severe than that of 35delG homozygotes. Several common mutations (M34T, V37I, and L90P) were associated with mild-to-moderate HI (median 25-40 dB). Two genotypes--35delG/R143W (median 105 dB) and 35delG/dela(GJB6-D13S1830) (median 108 dB)--had significantly more-severe HI than that of 35delG homozygotes.

The OPTION scale: measuring the extent that clinicians involve patients in decision-making tasks.

Abstract: OBJECTIVE: To examine the psychometric properties of a revised scale, named 'observing patient involvement in decision making' (OPTION), by analysing its reapplication to a sample of routine primary care consultations. The OPTION instrument assesses to what degree clinicians involve patients in decision making. DESIGN: Cross-sectional assessment of medical interaction by two calibrated raters. SETTING: Primary care. PARTICIPANTS: Twenty-one general practitioners provided 186 consultations for assessment. MEASUREMENTS: Observational score using the OPTION instrument. RESULTS: Compared with the first version of the OPTION scale, the revised scale that uses a magnitude instead of an attitude scale, when applied to the same data set, resulted in improvement in the scale's reliability and to lower scores for the levels of involvement achieved by the practitioners. Factor analysis confirms that it is acceptable to regard the scale as a single construct. Although there is moderate variability when raters are assessed on an item by item basis, the agreements between raters at the level of the overall OPTION score is high (the intraclass correlation coefficient scores for total OPTION score was 0.77), a level that is acceptable for the evaluation of a set of consultations per practitioner (e.g. between 5 and 10 consultations), where aggregate scores would be used for determining overall performance. CONCLUSIONS: We conclude that OPTION is sufficiently reliable to be used for formal assessment at the level of the whole instrument (all 12 items).