15,402 research outputs found
Atoms in double-delta-kicked periodic potentials: Chaos with long-range correlations
We report an experimental and theoretical study of the dynamics of cold atoms subjected to pairs of closely spaced pulses in an optical lattice. For all previously studied delta-kicked systems, chaotic classical dynamics shows diffusion with short-time (2- or 3-kick) correlations; here, chaotic diffusion combines with new types of long-ranged global correlations, between all kick pairs, which control transport through trapping regions in phase space. Correlations are studied in the classical regime, but the diffusive behavior observed in experiment depends on the quantum dynamical localization
Recruiting patients to medical research: double blind randomised trial of "opt-in" versus "opt-out" strategies
Objective To evaluate the effect of opt-in compared with opt-out recruitment strategies on response rate and selection bias. Design Double blind randomised controlled trial. Setting Two general practices in England. Participants 510 patients with angina. Intervention Patients were randomly allocated to an opt-in (asked to actively signal willingness to participate in research) or opt-out (contacted repeatedly unless they signalled unwillingness to participate) approach for recruitment to an observational prognostic study of patients with angina. Main outcome measures Recruitment rate and clinical characteristics of patients. Results The recruitment rate, defined by clinic attendance, was 38% (96/252) in the opt-in arm and 50% (128/258) in the opt-out arm (P = 0.014). Once an appointment had been made, non-attendance at the clinic was similar (20% opt-in arm v 17% opt-out arm; P = 0.86). Patients in the opt-in arm had fewer risk factors (44% v 60%; P = 0.053), less treatment for angina (69% v 82%; P = 0.010), and less functional impairment (9% v 20%; P = 0.023) than patients in the opt-out arm. Conclusions The opt-in approach to participant recruitment, increasingly required by ethics committees, resulted in lower response rates and a biased sample. We propose that the opt-out approach should be the default recruitment strategy for studies with low risk to participants
Azimuthal correlations of forward di-hadrons in d+Au collisions at RHIC in the Color Glass Condensate
We present a good description of recent experimental data on forward
di-hadron azimuthal correlations measured in deuteron-gold collisions at RHIC,
where monojet production has been observed. Our approach is based on the Color
Glass Condensate effective theory for the small-x degrees of freedom of the
nuclear wave function, including the use of non-linear evolution equations with
running QCD coupling. Our analysis provides further evidence for the presence
of saturation effects in RHIC data.Comment: 4 pages, 2 figures, version to appear in PR
A Fast and Scalable Graph Coloring Algorithm for Multi-core and Many-core Architectures
Irregular computations on unstructured data are an important class of
problems for parallel programming. Graph coloring is often an important
preprocessing step, e.g. as a way to perform dependency analysis for safe
parallel execution. The total run time of a coloring algorithm adds to the
overall parallel overhead of the application whereas the number of colors used
determines the amount of exposed parallelism. A fast and scalable coloring
algorithm using as few colors as possible is vital for the overall parallel
performance and scalability of many irregular applications that depend upon
runtime dependency analysis.
Catalyurek et al. have proposed a graph coloring algorithm which relies on
speculative, local assignment of colors. In this paper we present an improved
version which runs even more optimistically with less thread synchronization
and reduced number of conflicts compared to Catalyurek et al.'s algorithm. We
show that the new technique scales better on multi-core and many-core systems
and performs up to 1.5x faster than its predecessor on graphs with high-degree
vertices, while keeping the number of colors at the same near-optimal levels.Comment: To appear in the proceedings of Euro Par 201
Smart Content Recognition from Images Using a Mixture of Convolutional Neural Networks
With rapid development of the Internet, web contents become huge. Most of the
websites are publicly available, and anyone can access the contents from
anywhere such as workplace, home and even schools. Nevertheless, not all the
web contents are appropriate for all users, especially children. An example of
these contents is pornography images which should be restricted to certain age
group. Besides, these images are not safe for work (NSFW) in which employees
should not be seen accessing such contents during work. Recently, convolutional
neural networks have been successfully applied to many computer vision
problems. Inspired by these successes, we propose a mixture of convolutional
neural networks for adult content recognition. Unlike other works, our method
is formulated on a weighted sum of multiple deep neural network models. The
weights of each CNN models are expressed as a linear regression problem learned
using Ordinary Least Squares (OLS). Experimental results demonstrate that the
proposed model outperforms both single CNN model and the average sum of CNN
models in adult content recognition.Comment: To be published in LNEE, Code: github.com/mundher/NSF
Hypoxia Inducible Factor-Stabilizing Bioactive Glasses for Directing Mesenchymal Stem Cell Behavior.
How does zinc oxide-eugenol compare to ferric sulphate as a pulpotomy material?
KIMThis study compared the clinical and radiographic responses after 3 months to a sterile compression technique with zinc oxide-eugenol or 15.5% ferric sulphate in 145 pulpotomised primary teeth in 30 children. In both groups of teeth the success rate was 100%. These short-term results suggest that either technique may be used
'Just like a normal pain', what do people with diabetes mellitus experience when having a myocardial infarction: a qualitative study recruited from UK hospitals.
OBJECTIVE: The objective of the study was to investigate the symptoms people with diabetes experience when having a myocardial infarction (MI), their illness narrative and how they present their symptoms to the health service. SETTING: Three London (UK) hospitals (coronary care units and medical wards). PARTICIPANTS: Patients were recruited with diabetes mellitus (DM) (types 1 and 2) with a clinical presentation of MI (ST elevated MI (STEMI), non-ST elevated MI (NSTEMI), acute MI unspecified and cardiac arrest). A total of 43 participants were recruited, and 39 interviews met the study criteria and were analysed. They were predominantly male (n=30), aged 40-90 years and white British (18/39), and just over a half were from other ethnic groups. The majority had type 2 DM (n=35), 24 had an NSTEMI, 10 had an STEMI and five had other cardiac events. DEFINITIONS OF SELECTION/EXCLUSION CRITERIA: A diagnosis of MI and DM and the ability to communicate enough English to complete the interview. Ward staff made a clinical judgement that the participant was post-treatment, clinically stable and well enough to participate. METHODS: A qualitative study using taped and transcribed interviews analysed using a thematic analysis. RESULTS: While most participants did experience chest pain, it was often not their most striking symptom. As their chest pain did not match their expectations of what a 'heart attack' should be, participants developed narratives to explain these symptoms, including the symptoms being effects of their DM ('hypos'), side effects of medication (oral hypoglycaemics) or symptoms (such as breathlessness and indigestion) related to other comorbidities, often leading to delays in seeking care. CONCLUSIONS: While truly absent chest pain during MI among people with DM was rare in this study, patients' attenuated symptoms often led to delay in seeking attention, and this may result in delays in receiving treatment
Choosing the lesser of two evils, the better of two goods: Specifying the roles of ventromedial prefrontal cortex and dorsal anterior cingulate in object choice
The ventromedial prefrontal cortex (vmPFC) and dorsal anterior cingulate cortices (ACd) are considered important for reward-based decision making. However, work distinguishing their individual functional contributions has only begun. One aspect of decision making that has received little attention is that making the right choice often translates to making the better choice. Thus, response choice often occurs in situations where both options are desirable (e.g., choosing between mousse au chocolat or crème caramel cheesecake from a menu) or, alternatively, in situations where both options are undesirable. Moreover, response choice is easier when the reinforcements associated with the objects are far apart, rather than close together, in value. We used functional magnetic resonance imaging to delineate the functional roles of the vmPFC and ACd by investigating these two aspects of decision making: (1) decision form (i.e., choosing between two objects to gain the greater reward or the lesser punishment), and (2) between-object reinforcement distance (i.e., the difference in reinforcements associated with the two objects). Blood oxygen level-dependent (BOLD) responses within the ACd and vmPFC were both related to decision form but differentially. Whereas ACd showed greater responses when deciding between objects to gain the lesser punishment, vmPFC showed greater responses when deciding between objects to gain the greater reward. Moreover, vmPFC was sensitive to reinforcement expectations associated with both the chosen and the forgone choice. In contrast, BOLD responses within ACd, but not vmPFC, related to between-object reinforcement distance, increasing as the distance between the reinforcements of the two objects decreased. These data are interpreted with reference to models of ACd and vmPFC functioning
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