788 research outputs found
Relationship between cerebrospinal fluid neurodegeneration biomarkers and temporal brain atrophy in cognitively healthy older adults
It is unclear whether cerebrospinal fluid (CSF) biomarkers of neurodegeneration predict brain atrophy in cognitively healthy older adults, whether these associations can be explained by phosphorylated tau181 (p-tau) and the 42 amino acid form of amyloid-ęľ (Aęľ42) biomarkers, and which neural substrates may drive these associations. We addressed these questions in two samples of cognitively healthy older adults who underwent longitudinal structural MRI up to 7 years and had baseline CSF levels of heart-type fatty-acid binding protein [FABP3], total-tau, neurogranin, and neurofilament light [NFL] (n=189, scans=721). The results showed that NFL, total-tau, and FABP3 predicted entorhinal thinning and hippocampal atrophy. Brain atrophy was not moderated by Aęľ42 and the associations between NFL and FABP3 with brain atrophy were independent of p-tau. The spatial pattern of cortical atrophy associated with the biomarkers overlapped with neurogenetic profiles associated with expression in the axonal (total-tau, NFL) and dendritic (neurogranin) components. CSF biomarkers of neurodegeneration are useful for predicting specific features of brain atrophy in older adults, independently of amyloid and tau pathology biomarkers
Nonlinear atom interferometer surpasses classical precision limit
Interference is fundamental to wave dynamics and quantum mechanics. The
quantum wave properties of particles are exploited in metrology using atom
interferometers, allowing for high-precision inertia measurements [1, 2].
Furthermore, the state-of-the-art time standard is based on an interferometric
technique known as Ramsey spectroscopy. However, the precision of an
interferometer is limited by classical statistics owing to the finite number of
atoms used to deduce the quantity of interest [3]. Here we show experimentally
that the classical precision limit can be surpassed using nonlinear atom
interferometry with a Bose-Einstein condensate. Controlled interactions between
the atoms lead to non-classical entangled states within the interferometer;
this represents an alternative approach to the use of non-classical input
states [4-8]. Extending quantum interferometry [9] to the regime of large atom
number, we find that phase sensitivity is enhanced by 15 per cent relative to
that in an ideal classical measurement. Our nonlinear atomic beam splitter
follows the "one-axis-twisting" scheme [10] and implements interaction control
using a narrow Feshbach resonance. We perform noise tomography of the quantum
state within the interferometer and detect coherent spin squeezing with a
squeezing factor of -8.2dB [11-15]. The results provide information on the
many-particle quantum state, and imply the entanglement of 170 atoms [16]
Shell chemistry of the boreal Campanian bivalve Rastellum diluvianum (Linnaeus, 1767) reveals temperature seasonality, growth rates and life cycle of an extinct Cretaceous oyster
This is the final version. Available from European Geosciences Union (EGU) / Copernicus Publications via the DOI in this record.âŻThe Campanian age (Late Cretaceous) is characterized by a warm greenhouse climate with limited land-ice volume. This makes this period an ideal target for studying climate dynamics during greenhouse periods, which are essential for predictions of future climate change due to anthropogenic greenhouse gas emissions. Well-preserved fossil shells from the Campanian (Âą78âMa) high mid-latitude (50ââN) coastal faunas of the Kristianstad Basin (southern Sweden) offer a unique snapshot of short-term climate and environmental variability, which complements existing long-term climate reconstructions. In this study, we apply a combination of high-resolution spatially resolved trace element analyses (micro-X-ray fluorescence â ÂľXRF â and laser ablation inductively coupled plasma mass spectrometry â LA-ICP-MS), stable isotope analyses (IRMS) and growth modeling to study short-term (seasonal) variations recorded in the oyster species Rastellum diluvianum from the IvĂś Klack locality. Geochemical records through 12 specimens shed light on the influence of specimen-specific and ontogenetic effects on the expression of seasonal variations in shell chemistry and allow disentangling vital effects from environmental influences in an effort to refine paleoseasonality reconstructions of Late Cretaceous greenhouse climates. Growth models based on stable oxygen isotope records yield information on the mode of life, circadian rhythm and reproductive cycle of these extinct oysters. This multi-proxy study reveals that mean annual temperatures in the Campanian higher mid-latitudes were 17 to 19ââC, with winter minima of âź13ââC and summer maxima of 26ââC, assuming a Late Cretaceous seawater oxygen isotope composition of â1ââ° VSMOW (Vienna standard mean ocean water). These results yield smaller latitudinal differences in temperature seasonality in the Campanian compared to today. Latitudinal temperature gradients were similar to the present, contrasting with previous notions of âequable climateâ during the Late Cretaceous. Our results also demonstrate that species-specific differences and uncertainties in the composition of Late Cretaceous seawater prevent trace element proxies (MgâCa, SrâCa, MgâLi and SrâLi) from being used as reliable temperature proxies for fossil oyster shells. However, trace element profiles can serve as a quick tool for diagenesis screening and investigating seasonal growth patterns in ancient shells.Flemish Institute for Science and Technology (IWT)Hercules InfrastructureFWOBelspo BRAIN ProjectCarlsbergfondetVUB Strategic Research
Alcoholic cirrhosis in Denmark â population-based incidence, prevalence, and hospitalization rates between 1988 and 2005: A descriptive cohort study
<p>Abstract</p> <p>Background</p> <p>Denmark has one of the highest alcohol consumption rates in Northern Europe. The overall per capita alcohol consumption has been stable in recent decades, but surveys have indicated that consumption has decreased in the young and increased in the old. However, there is no recent information on the epidemiology of alcoholic cirrhosis. We examined time trends in incidence, prevalence, and hospitalization rates of alcoholic cirrhosis in Denmark between 1988 and 2005.</p> <p>Methods</p> <p>We used data from a nationwide population-based hospital registry to identify all Danish citizens with a hospital diagnosis of alcoholic cirrhosis. We computed standardized incidence rates, prevalence and hospitalization rates of alcoholic cirrhosis within the Danish population. We also computed the number of hospitalizations per alcoholic cirrhosis patient per year.</p> <p>Results</p> <p>From 1988 to 1993, incidence rates for men and women of any age showed no clear trend, and after a 32 percent increase in 1994, rates were stable throughout 2005. In 2001â2005, the incidence rates were 265 and 118 per 1,000,000 per year for men and women, respectively, and the prevalence rates were 1,326 and 701 per 1,000,000. From 1994, incidence, prevalence, and hospitalization rates decreased for men and women younger than 45 years and increased in the older population, although the latter finding might be partly explained by changes in coding practice. Men and women born around 1960 or later had progressively lower age-specific alcoholic cirrhosis incidence rates than the generations before them. From 1996 to 2005, the number of hospitalizations per alcoholic cirrhosis patient per year increased from 1.3 to 1.5 for men and from 1.1 to 1.2 for women.</p> <p>Conclusion</p> <p>From 1988 to 2005, alcoholic cirrhosis put an increasing burden on the Danish healthcare system. However, the decreasing incidence rate in the population younger than 45 years from 1994 indicated that men and women born around 1960 or later had progressively lower incidence rates than the generations before them. Therefore, we expect the overall incidence and prevalence rates of alcoholic cirrhosis to decrease in the future.</p
Quantum Non-Demolition Detection of Strongly Correlated Systems
Preparation, manipulation, and detection of strongly correlated states of
quantum many body systems are among the most important goals and challenges of
modern physics. Ultracold atoms offer an unprecedented playground for
realization of these goals. Here we show how strongly correlated states of
ultracold atoms can be detected in a quantum non-demolition scheme, that is, in
the fundamentally least destructive way permitted by quantum mechanics. In our
method, spatially resolved components of atomic spins couple to quantum
polarization degrees of freedom of light. In this way quantum correlations of
matter are faithfully mapped on those of light; the latter can then be
efficiently measured using homodyne detection. We illustrate the power of such
spatially resolved quantum noise limited polarization measurement by applying
it to detect various standard and "exotic" types of antiferromagnetic order in
lattice systems and by indicating the feasibility of detection of superfluid
order in Fermi liquids.Comment: Published versio
Replacement therapy for bleeding episodes in factor VII deficiency: A prospective evaluation
Patients with inherited factor VII (FVII) deficiency display different clinical phenotypes requiring ad hoc management. This study evaluated treatments for spontaneous and traumatic bleeding using data from the Seven Treatment Evaluation Registry (STER). One-hundred one bleeds were analysed in 75 patients (41 females; FVII coagulant activity <1-20%). Bleeds were grouped as haemarthroses (n=30), muscle/subcutaneous haematomas (n=16), epistaxis (n=12), gum bleeding (n=13), menorrhagia (n=16), central nervous system (CNS; n=9), gastrointestinal (GI; n=2) and other (n=3). Of 93 evaluable episodes, 76 were treated with recombinant, activated FVII (rFVIIa), eight with fresh frozen plasma (FFP), seven with plasma-derived FVII (pdFVII) and two with prothrombin-complex concentrates. One-day replacement therapy resulted in very favourable outcomes in haemarthroses, and was successful in muscle/subcutaneous haematomas, epistaxis and gum bleeding. For menorrhagia, single- or multiple-dose schedules led to favourable outcomes. No thrombosis occurred; two inhibitors were detected in two repeatedly treated patients (one post-rFVIIa, one post-pdFVII). In FVII deficiency, most bleeds were successfully treated with single 'intermediate' doses (median 60 ¾g/kg) of rFVIIa. For the most severe bleeds (CNS, GI) short- or long-term prophylaxis may be optimalPatients with inherited factor VII (FVII) deficiency display different clinical phenotypes requiring ad hoc management. This study evaluated treatments for spontaneous and traumatic bleeding using data from the Seven Treatment Evaluation Registry (STER). One-hundred one bleeds were analysed in 75 patients (41 females; FVII coagulant activity <1-20%). Bleeds were grouped as haemarthroses (n=30), muscle/subcutaneous haematomas (n=16), epistaxis (n=12), gum bleeding (n=13), menorrhagia (n=16), central nervous system (CNS; n=9), gastrointestinal (GI; n=2) and other (n=3). Of 93 evaluable episodes, 76 were treated with recombinant, activated FVII (rFVIIa), eight with fresh frozen plasma (FFP), seven with plasma-derived FVII (pdFVII) and two with prothrombin-complex concentrates. One-day replacement therapy resulted in very favourable outcomes in haemarthroses, and was successful in muscle/subcutaneous haematomas, epistaxis and gum bleeding. For menorrhagia, single- or multiple-dose schedules led to favourable outcomes. No thrombosis occurred; two inhibitors were detected in two repeatedly treated patients (one postrFVIIa, one post-pdFVII). In FVII deficiency, most bleeds were successfully treated with single 'intermediate' doses (median 60 Οg/kg) of rFVIIa. For the most severe bleeds (CNS, GI) short- or long-term prophylaxis may be optimal. Š Schattauer 2013
Future costs in cost-effectiveness analysis: an empirical assessment
To assess the usage of cost-utility analysis (CUA) in oral health interventions and to evaluate the methods used and the reporting quality of CUA in publications on oral health interventions
Towards fault-tolerant quantum computing with trapped ions
Today ion traps are among the most promising physical systems for
constructing a quantum device harnessing the computing power inherent in the
laws of quantum physics. The standard circuit model of quantum computing
requires a universal set of quantum logic gates for the implementation of
arbitrary quantum operations. As in classical models of computation, quantum
error correction techniques enable rectification of small imperfections in gate
operations, thus allowing for perfect computation in the presence of noise. For
fault-tolerant computation, it is commonly believed that error thresholds
ranging between 10^-4 and 10^-2 will be required depending on the noise model
and the computational overhead for realizing the quantum gates. Up to now, all
experimental implementations have fallen short of these requirements. Here, we
report on a Molmer-Sorensen type gate operation entangling ions with a fidelity
of 99.3(1)% which together with single-qubit operations forms a universal set
of quantum gates. The gate operation is performed on a pair of qubits encoded
in two trapped calcium ions using a single amplitude-modulated laser beam
interacting with both ions at the same time. A robust gate operation, mapping
separable states onto maximally entangled states is achieved by adiabatically
switching the laser-ion coupling on and off. We analyse the performance of a
single gate and concatenations of up to 21 gate operations. The gate mechanism
holds great promise not only for two-qubit but also for multi-qubit operations.Comment: submitted to Nature Physic
Validity of claims made in weight management research: a narrative review of dietetic articles
<p>Abstract</p> <p>Background</p> <p>The best available evidence demonstrates that conventional weight management has a high long-term failure rate. The ethical implications of continued reliance on an energy deficit approach to weight management are under-explored.</p> <p>Methods</p> <p>A narrative literature review of journal articles in <it>The Journal of Human Nutrition and Dietetics </it>from 2004 to 2008.</p> <p>Results</p> <p>Although the energy deficit approach to weight management has a high long-term failure rate it continues to dominate research in the field. In the current research agenda, controversies and complexities in the evidence base are inadequately discussed, and claims about the likely success of weight management misrepresent available evidence.</p> <p>Conclusions</p> <p>Dietetic literature on weight management fails to meet the standards of evidence based medicine. Research in the field is characterised by speculative claims that fail to accurately represent the available data. There is a corresponding lack of debate on the ethical implications of continuing to promote ineffective treatment regimes and little research into alternative non-weight centred approaches. An alternative health at every size approach is recommended.</p
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