154 research outputs found
Longevity of immediate rehabilitation with direct metal-wire reinforced composite fixed partial dentures.
OBJECTIVES
This study aimed to analyze the longevity of direct metal-wire reinforced composite fixed partial dentures (MRC-FPD) and factors influencing their survival and success.
METHODS
Within one private practice 513 MRC-FPD were directly applied. The preparation of a proximal cavity in abutment teeth was not limited. MRC-FPD were reinforced by one to three metal-wires. At the last follow-up MRC-FPD were considered successful, if they were still in function without any need of therapy. MRC-FPD were considered as survived, if they were repaired or replaced. Multi-level Cox proportional hazard models were used to evaluate the association between clinical factors and time.
RESULTS
Mean follow-up period (range) was 59(2-249) months. Seventy-three bridges did not survive (cumulative survival rate(CSR):86%) and further 129 bridges had received a restorative follow-up treatment (CSR:61%). AFR was 2.2% for survival and 8.6% for success. In multivariate analysis MRC-FPD with> 1 wire showed a up to 2.3x higher failure rate than MRC-FPD with one wire(p ≤ 0.023). Dentist's experience in designing MRC-FDP (p ≤ 0.017), patient's caries risk (p ≤ 0.040) and bruxism (p = 0.033) significantly influenced the failure rate: the more experience, the lower caries risk and bruxism, the lower the failure rate.
SIGNIFICANCE
For directly prepared metal-wire reinforced composite bridges high survival and moderate success rates were observed. MRC-FPD might, thus, be an immediate, short- and medium-term solution for replacing missing teeth. However, several factors on the levels of practice (dentist's experience in designing MRC-FDP), patient (bruxism, caries risk) and restoration (number of wires) were identified as significant predictors for the failure rate. The study was registered in the German Clinical Trials Register (DRKS-ID: DRKS00021576)
Self-Testing of Physical Theories, or, Is Quantum Theory Optimal with Respect to Some Information-Processing Task?
Self-testing usually refers to the task of taking a given set of observed
correlations that are assumed to arise via a process that is accurately
described by quantum theory, and trying to infer the quantum state and
measurements. In other words it is concerned with the question of whether we
can tell what quantum black-box devices are doing by looking only at their
input-output behaviour and is known to be possible in several cases. Here we
introduce a more general question: is it possible to self-test a theory, and,
in particular, quantum theory? More precisely, we ask whether within a
particular causal structure there are tasks that can only be performed in
theories that have the same correlations as quantum mechanics in any scenario.
We present a candidate task for such a correlation self-test and analyse it in
a range of generalised probabilistic theories (GPTs), showing that none of
these perform better than quantum theory. A generalisation of our results
showing that all non-quantum GPTs are strictly inferior to quantum mechanics
for this task would point to a new way to axiomatise quantum theory, and enable
an experimental test that simultaneously rules out such GPTs.Comment: 6 pages; v2: close to published version; v3: typos correcte
Physical and psychological health of medical students involved in the coronavirus disease 2019 response in Switzerland.
Students involved in the COVID-19 response reported a similar proportion of COVID-19 symptoms or confirmed diagnoses, but lower levels of anxiety, depression and burnout compared with their non-involved peers
Inability of the entropy vector method to certify nonclassicality in linelike causal structures
Bell's theorem shows that our intuitive understanding of causation must be
overturned in light of quantum correlations. Nevertheless, quantum mechanics
does not permit signalling and hence a notion of cause remains. Understanding
this notion is not only important at a fundamental level, but also for
technological applications such as key distribution and randomness expansion.
It has recently been shown that a useful way to decide which classical causal
structures could give rise to a given set of correlations is to use entropy
vectors. These are vectors whose components are the entropies of all subsets of
the observed variables in the causal structure. The entropy vector method
employs causal relationships among the variables to restrict the set of
possible entropy vectors. Here, we consider whether the same approach can lead
to useful certificates of non-classicality within a given causal structure.
Surprisingly, we find that for a family of causal structures that include the
usual bipartite Bell structure they do not. For all members of this family, no
function of the entropies of the observed variables gives such a certificate,
in spite of the existence of nonclassical correlations. It is therefore
necessary to look beyond entropy vectors to understand cause from a quantum
perspective.Comment: 5 pages + appendix, v2: added references, v3: new title, added
journal referenc
Secondary user relations in emerging mobile computing environments
Mobile technologies are enabling access to information in diverse environ.ments, and are exposing a wider group of individuals to said technology. Therefore, this paper proposes that a wider view of user relations than is usually considered in information systems research is required. Specifically, we examine the potential effects of emerging mobile technologies on end-‐user relations with a focus on the ‘secondary user’, those who are not intended to interact directly with the technology but are intended consumers of the technology’s output. For illustration, we draw on a study of a U.K. regional Fire and Rescue Service and deconstruct mobile technology use at Fire Service incidents. Our findings provide insights, which suggest that, because of the nature of mobile technologies and their context of use, secondary user relations in such emerging mobile environments are important and need further exploration
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Don’t get too close to me: depressed and non-depressed survivors of child maltreatment prefer larger comfortable interpersonal distances towards strangers
Background: Childhood maltreatment (CM) is frequently linked to interpersonal problems such as diffi-culties in social relationships, loneliness, and isolation. These difficulties might partly stem from trou-bles regulating comfortable interpersonal distance (CIPD).
Objective: We experimentally investigated whether CM manifests in larger CIPD and whether all sub-types of CM (i.e., physical, emotional, or sexual abuse and physical or emotional neglect) affect CIPD.
Methods: Using the stop-distance method (i.e., a team member approached participants until the lat-ter indicated discomfort), we assessed CIPD in 84 adults with a self-reported history of CM (24 with depressive symptoms) and 57 adult controls without a history of CM (without depressive symptoms).
Results: Adults with CM showed a larger CIPD (Mdn = 86 cm) than controls (Mdn = 68 cm), and CIPD was largest for those with CM combined with current depressive symptoms (Mdn = 145 cm) (p’s < .047). In the latter group, all subtypes of CM were associated with a larger CIPD compared to controls (p’s < .045). In the CM group without depressive symptoms, only those with emotional abuse (p = .040) showed a larger CIPD than controls.
Conclusions: These results add to findings of differential socio-emotional long-term consequences of CM, depending upon the subtype of CM. Future research should explore whether a larger CIPD has a negative impact on social functioning in individuals exposed to CM, particularly in those with depres-sive symptoms
Increased Na+/Ca2+ exchanger expression/activity constitutes a point of inflection in the progression to heart failure of hypertensive rats
Spontaneously hypertensive rat (SHR) constitutes a genetic model widely used to study the natural evolution of hypertensive heart disease. Ca 2+-handling alterations are known to occur in SHR. However, the putative modifications of Ca2+-handling proteins during the progression to heart failure (HF) are not well established. Moreover, the role of apoptosis in SHR is controversial. We investigated intracellular Ca 2+, Ca2+-handling proteins and apoptosis in SHR vs. control Wistar rats (W) from 3 to 15 months (mo). Changes associated with the transition to HF (i.e. lung edema and decrease in midwall fractional shortening), occurred at 15 mo in 38% of SHR (SHRF). In SHRF, twitch and caffeine-induced Ca2+ transients, significantly decreased relative to 6/9 mo and 15 mo without HF signs. This decrease occurred in association with a decrease in the time constant of caffeine-Ca2+ transient decay and an increase in Na+/Ca2+ exchanger (NCX) abundance (p< 0.05) with no changes in SERCA2a expression/activity. An increased Ca 2+-calmodulin-kinase II activity, associated with an enhancement of apoptosis (TUNEL and Bax/Bcl2) was observed in SHR relative to W from 3 to 15 mo. Conclusions: 1. Apoptosis is an early and persistent event that may contribute to hypertrophic remodeling but would not participate in the contractile impairment of SHRF. 2. The increase in NCX expression/activity, associated with an increase in Ca2+ efflux from the cell, constitutes a primary alteration of Ca2+-handling proteins in the evolution to HF. 3. No changes in SERCA2a expression/activity are observed when HF signs become evident.Centro de Investigaciones CardiovascularesFacultad de Ciencias Veterinaria
Axiomatic relation between thermodynamic and information-theoretic entropies
Thermodynamic entropy, as defined by Clausius, characterizes macroscopic observations of a system based on phenomenological quantities such as temperature and heat. In contrast, information-theoretic entropy, introduced by Shannon, is a measure of uncertainty. In this Letter, we connect these two notions of entropy, using an axiomatic framework for thermodynamics [Lieb, Yngvason, Proc. Roy. Soc.(2013)]. In particular, we obtain a direct relation between the Clausius entropy and the Shannon entropy, or its generalisation to quantum systems, the von Neumann entropy. More generally, we find that entropy measures relevant in non-equilibrium thermodynamics correspond to entropies used in one-shot information theory
Predicting Many Properties of a Quantum System from Very Few Measurements
Predicting the properties of complex, large-scale quantum systems is essential for developing quantum technologies. We present an efficient method for constructing an approximate classical description of a quantum state using very few measurements of the state. This description, called a ‘classical shadow’, can be used to predict many different properties; order log(M) measurements suffice to accurately predict M different functions of the state with high success probability. The number of measurements is independent of the system size and saturates information-theoretic lower bounds. Moreover, target properties to predict can be selected after the measurements are completed. We support our theoretical findings with extensive numerical experiments. We apply classical shadows to predict quantum fidelities, entanglement entropies, two-point correlation functions, expectation values of local observables and the energy variance of many-body local Hamiltonians. The numerical results highlight the advantages of classical shadows relative to previously known methods
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