Abrupt transition in quasiparticle dynamics at optimal doping in a cuprate superconductor system

We report time-resolved measurements of the photoinduced change in reflectivity, Delta R, in the Bi2Sr2Ca(1-y)Dy(y)Cu2O(8+delta) (BSCCO) system of cuprate superconductors as a function of hole concentration. We find that the kinetics of quasiparticle decay and the sign of Delta R both change abruptly where the superconducting transition temperature Tc is maximal. These coincident changes suggest that a sharp transition in quasiparticle dynamics takes place precisely at optimal doping in the BSCCO system.Comment: 10 pages, 4 figure

CacheZoom: How SGX Amplifies The Power of Cache Attacks

In modern computing environments, hardware resources are commonly shared, and parallel computation is widely used. Parallel tasks can cause privacy and security problems if proper isolation is not enforced. Intel proposed SGX to create a trusted execution environment within the processor. SGX relies on the hardware, and claims runtime protection even if the OS and other software components are malicious. However, SGX disregards side-channel attacks. We introduce a powerful cache side-channel attack that provides system adversaries a high resolution channel. Our attack tool named CacheZoom is able to virtually track all memory accesses of SGX enclaves with high spatial and temporal precision. As proof of concept, we demonstrate AES key recovery attacks on commonly used implementations including those that were believed to be resistant in previous scenarios. Our results show that SGX cannot protect critical data sensitive computations, and efficient AES key recovery is possible in a practical environment. In contrast to previous works which require hundreds of measurements, this is the first cache side-channel attack on a real system that can recover AES keys with a minimal number of measurements. We can successfully recover AES keys from T-Table based implementations with as few as ten measurements.Comment: Accepted at Conference on Cryptographic Hardware and Embedded Systems (CHES '17

Parents' responses to prognostic disclosure at diagnosis of a child with a high‐risk brain tumor: Analysis of clinician‐parent interactions and implications for clinical practice

Background: Previous studies have found that parents of children with cancer desire more prognostic information than is often given even when prognosis is poor. We explored in audio‐recorded consultations the kinds of information they seek. / Methods: Ethnographic study including observation and audio recording of consultations at diagnosis. Consultations were transcribed and analyzed using an interactionist perspective including tools drawn from conversation and discourse analysis. / Results: Enrolled 21 parents and 12 clinicians in 13 cases of children diagnosed with a high‐risk brain tumor (HRBT) over 20 months at a tertiary pediatric oncology center. Clinicians presented prognostic information in all cases. Through their questions, parents revealed what further information they desired. Clinicians made clear that no one could be absolutely certain what the future held for an individual child. Explicit communication about prognosis did not satisfy parents’ desire for information about their own child. Parents tried to personalize prognostic information and to apply it to their own situation. Parents moved beyond prognostic information presented and drew conclusions, which could change over time. Parents who were present in the same consultations could form different views of their child's prognosis. / Conclusion: Population level prognostic information left parents uncertain about their child's future. The need parents revealed was not for more such information but rather how to use the information given and how to apply it to their child in the face of such uncertainty. Further research is needed on how best to help parents deal with uncertainty and make prognostic information actionable

Clinical performance of bleeding risk scores for predicting major and clinically relevant non-major bleeding events in patients receiving warfarin

Background: Oral anticoagulant therapy is associated with an increased risk of hemorrhage, which can be assessed by bleeding risk scores. We evaluated the performance of five validated scores for predicting major and clinically relevant non-major bleeding events in patients receiving warfarin. Methods and results: We conducted an ambispective, single-center cohort study of 321 consecutive patients enrolled in an academic anticoagulation clinic. The following scores were calculated: modified Outpatient Bleeding Risk Index, Contemporary Bleeding Risk Model, HEMORR2HAGES (Hepatic or Renal Disease, Ethanol Abuse, Malignancy, Older Age, Reduced Platelet Count or Function, Re-Bleeding, Hypertension, Anemia, Genetic Factors, Excessive Fall Risk and Stroke), ATRIA (Anticoagulation and Risk Factors in Atrial Fibrillation), and HAS-BLED (Hypertension, Abnormal Renal/Liver Function, Stroke, Bleeding History or Predisposition, Labile International Normalized Ratio, Elderly, Drugs/Alcohol). Main outcomes were major bleeding and a composite of major plus clinically relevant non-major bleeding. Incidence rates for all group were 3.8 (95% confidence interval [CI] 2.0-6.4) and 11.9 (95% CI 8.6-16.4) events per 100 patient-years for major bleeding and major plus clinically relevant non-major bleeding, respectively. Agreement among the five scores was low to moderate (Kendall\u27s tau-b coefficients 0.22-0.54). For major bleeding, the c-statistics ranged from 0.606 to 0.735, whereas for major plus clinically relevant non-major bleeding, they ranged from 0.549 to 0.613. For all scores, the 95% CI for the c-statistics crossed 0.5 or was very close. Among high-risk patients, the hazard ratios for major bleeding ranged from 0.90 to 39.01, whereas for major plus clinically relevant non-major bleeding, they ranged from 1.52 to 8.71. For intermediate-risk patients, no score, except the Contemporary Bleeding Risk Model, produced statistically significant hazard ratios. Conclusion: The scores demonstrated poor agreement and low to moderate discriminatory ability. General clinical implementation of these scores cannot be recommended yet. © 2013 International Society on Thrombosis and Haemostasis

Ferromagnetic Enhancement of CE-type Spin Ordering in (Pr,Ca)MnO3_3

We present resonant soft X-ray scattering (RSXS) results from small band width manganites (Pr,Ca)MnO$_3$, which show that the CE-type spin ordering (SO) at the phase boundary is stabilized only below the canted antiferromagnetic transition temperature and enhanced by ferromagnetism in the macroscopically insulating state (FM-I). Our results reveal the fragility of the CE-type ordering that underpins the colossal magnetoresistance (CMR) effect in this system, as well as an unexpected cooperative interplay between FM-I and CE-type SO which is in contrast to the competitive interplay between the ferromagnetic metallic (FM-M) state and CE-type ordering.Comment: Accepted for publication in Phys. Rev. Let

The FiDel model at 7 TeV

After the long shut down of 2013-2014, the LHC energy will be pushed toward 7 TeV. In this range of energy, the main magnets will enter a new regime. For this reason, this paper will present a detailed study of the performance of the FiDeL model that could be critical for the operation in 2015. In particular this paper will study the saturation component and its precision in the model, the errors due to the hysteresis, and an estimate of the dynamic effects for the 7 TeV operation.peer-reviewe

Nonlinear Dynamics of the Perceived Pitch of Complex Sounds

We apply results from nonlinear dynamics to an old problem in acoustical physics: the mechanism of the perception of the pitch of sounds, especially the sounds known as complex tones that are important for music and speech intelligibility

Ophthalmic magnetic resonance imaging at 7.0 T using a 6-channel transceiver radiofrequency coil array in healthy subjects and patients with intraocular masses

OBJECTIVES: This study was designed to examine the feasibility of ophthalmic magnetic resonance imaging (MRI) at 7.0 T using a local 6-channel transmit/receive radiofrequency (RF) coil array in healthy volunteers and patients with intraocular masses. MATERIALS AND METHODS: A novel 6-element transceiver RF coil array that makes uses of loop elements and that is customized for eye imaging at 7.0 T is proposed. Considerations influencing the RF coil design and the characteristics of the proposed RF coil array are presented. Numerical electromagnetic field simulations were conducted to enhance the RF coil characteristics. Specific absorption rate simulations and a thorough assessment of RF power deposition were performed to meet the safety requirements. Phantom experiments were carried out to validate the electromagnetic field simulations and to assess the real performance of the proposed transceiver array. Certified approval for clinical studies was provided by a local notified body before the in vivo studies. The suitability of the RF coil to image the human eye, optical nerve, and orbit was examined in an in vivo feasibility study including (a) 3-dimensional (3D) gradient echo (GRE) imaging, (b) inversion recovery 3D GRE imaging, and (c) 2D T2-weighted fast spin-echo imaging. For this purpose, healthy adult volunteers (n = 17; mean age, 34 +- 11 years) and patients with intraocular masses (uveal melanoma, n = 5; mean age, 57 +- 6 years) were investigated. RESULTS: All subjects tolerated all examinations well with no relevant adverse events. The 6-channel coil array supports high-resolution 3D GRE imaging with a spatial resolution as good as 0.2 × 0.2 × 1.0 mm, which facilitates the depiction of anatomical details of the eye. Rather, uniform signal intensity across the eye was found. A mean signal-to-noise ratio of approximately 35 was found for the lens, whereas the vitreous humor showed a signal-to-noise ratio of approximately 30. The lens-vitreous humor contrast-to-noise ratio was 8, which allows good differentiation between the lens and the vitreous compartment. Inversion recovery prepared 3D GRE imaging using a spatial resolution of 0.4 × 0.4 × 1.0 mm was found to be feasible. T2-weighted 2D fast spin-echo imaging with the proposed RF coil afforded a spatial resolution of 0.25 × 0.25 × 0.7 mm. CONCLUSIONS: This work provides valuable information on the feasibility of ophthalmic MRI at 7.0 T using a dedicated 6-channel transceiver coil array that supports the acquisition of high-contrast, high-spatial resolution images in healthy volunteers and patients with intraocular masses. The results underscore the challenges of ocular imaging at 7.0 T and demonstrate that these issues can be offset by using tailored RF coil hardware. The benefits of such improvements would be in positive alignment with explorations that are designed to examine the potential of MRI for the assessment of spatial arrangements of the eye segments and their masses with the ultimate goal to provide imaging means for guiding treatment decisions in ophthalmological diseases