Verifiable Blind Quantum Computing with Trapped Ions and Single Photons.

We report the first hybrid matter-photon implementation of verifiable blind quantum computing. We use a trapped-ion quantum server and a client-side photonic detection system networked via a fiber-optic quantum link. The availability of memory qubits and deterministic entangling gates enables interactive protocols without postselection-key requirements for any scalable blind server, which previous realizations could not provide. We quantify the privacy at ≲0.03 leaked classical bits per qubit. This experiment demonstrates a path to fully verified quantum computing in the cloud.

Establishing an updated consensus on the conceptual and operational definitions of Making Every Contact Count (MECC) across experts within research and practice: an international Delphi Study.

OBJECTIVES: The Making Every Contact Count (MECC) initiative is broadly defined as an opportunistic approach to prevention by making use of the thousands of conversations service providers have with service users every day. However, since its conception, the application of MECC has diverged and developed considerably. Thus, the current study aimed to revise the definition according to current research and practice to better describe what is and is not included. STUDY DESIGN: A consensus building classic Delphi methodology, completed by an expert panel. METHODS: Round 1 asked open questions around the definition of MECC. Content analysis of round 1 identified statements that were rated for agreement in round 2. Statements achieving ≥80% agreement were included in a short, long, or operational definition of MECC that were rated for agreement in round 3 (the minimum number required). An agreement of ≥80% indicated consensus. RESULTS: Forty out of 100 contacted experts completed three rounds. Experts in practice and research were recruited internationally although most were from England. From round 1, 274 statements were generated, of which 96 achieved consensus and were included within round 3. The short and long definition received consensus in round 3, the operational definition required four rounds to reach consensus. CONCLUSIONS: MECC is a person-centred approach to health behaviour change that, provided an individual possesses the relevant skills, can be delivered by anyone and anywhere. The distinguishing feature of MECC is not in its duration, target behaviour, or conditions for delivery, but rather in the approach taken and the mechanisms applied to conversations. Implications for research and practice are discussed, and the limits for applicability acknowledged.

Robust Quantum Memory in a Trapped-Ion Quantum Network Node.

We integrate a long-lived memory qubit into a mixed-species trapped-ion quantum network node. Ion-photon entanglement first generated with a network qubit in ^{88}Sr^{+} is transferred to ^{43}Ca^{+} with 0.977(7) fidelity, and mapped to a robust memory qubit. We then entangle the network qubit with a second photon, without affecting the memory qubit. We perform quantum state tomography to show that the fidelity of ion-photon entanglement decays ∼70 times slower on the memory qubit. Dynamical decoupling further extends the storage duration; we measure an ion-photon entanglement fidelity of 0.81(4) after 10 s.

An elementary quantum network of entangled optical atomic clocks.

Optical atomic clocks are our most precise tools to measure time and frequency1-3. Precision frequency comparisons between clocks in separate locations enable one to probe the space-time variation of fundamental constants4,5 and the properties of dark matter6,7, to perform geodesy8-10 and to evaluate systematic clock shifts. Measurements on independent systems are limited by the standard quantum limit; measurements on entangled systems can surpass the standard quantum limit to reach the ultimate precision allowed by quantum theory-the Heisenberg limit. Although local entangling operations have demonstrated this enhancement at microscopic distances11-16, comparisons between remote atomic clocks require the rapid generation of high-fidelity entanglement between systems that have no intrinsic interactions. Here we report the use of a photonic link17,18 to entangle two 88Sr+ ions separated by a macroscopic distance19 (approximately 2 m) to demonstrate an elementary quantum network of entangled optical clocks. For frequency comparisons between the ions, we find that entanglement reduces the measurement uncertainty by nearly [Formula: see text], the value predicted for the Heisenberg limit. Today's optical clocks are typically limited by dephasing of the probe laser20; in this regime, we find that entanglement yields a factor of 2 reduction in the measurement uncertainty compared with conventional correlation spectroscopy techniques20-22. We demonstrate this enhancement for the measurement of a frequency shift applied to one of the clocks. This two-node network could be extended to additional nodes23, to other species of trapped particles or-through local operations-to larger entangled systems.

Experimental quantum key distribution certified by Bell's theorem.

Cryptographic key exchange protocols traditionally rely on computational conjectures such as the hardness of prime factorization1 to provide security against eavesdropping attacks. Remarkably, quantum key distribution protocols such as the Bennett-Brassard scheme2 provide information-theoretic security against such attacks, a much stronger form of security unreachable by classical means. However, quantum protocols realized so far are subject to a new class of attacks exploiting a mismatch between the quantum states or measurements implemented and their theoretical modelling, as demonstrated in numerous experiments3-6. Here we present the experimental realization of a complete quantum key distribution protocol immune to these vulnerabilities, following Ekert's pioneering proposal7 to use entanglement to bound an adversary's information from Bell's theorem8. By combining theoretical developments with an improved optical fibre link generating entanglement between two trapped-ion qubits, we obtain 95,628 key bits with device-independent security9-12 from 1.5 million Bell pairs created during eight hours of run time. We take steps to ensure that information on the measurement results is inaccessible to an eavesdropper. These measurements are performed without space-like separation. Our result shows that provably secure cryptography under general assumptions is possible with real-world devices, and paves the way for further quantum information applications based on the device-independence principle.

High-Rate, High-Fidelity Entanglement of Qubits Across an Elementary Quantum Network.

We demonstrate remote entanglement of trapped-ion qubits via a quantum-optical fiber link with fidelity and rate approaching those of local operations. Two ^{88}Sr^{+} qubits are entangled via the polarization degree of freedom of two spontaneously emitted 422 nm photons which are coupled by high-numerical-aperture lenses into single-mode optical fibers and interfere on a beam splitter. A novel geometry allows high-efficiency photon collection while maintaining unit fidelity for ion-photon entanglement. We generate heralded Bell pairs with fidelity 94% at an average rate 182 s^{-1} (success probability 2.18×10^{-4}).

A short response time atomic source for trapped ion experiments.

Ion traps are often loaded from atomic beams produced by resistively heated ovens. We demonstrate an atomic oven which has been designed for fast control of the atomic flux density and reproducible construction. We study the limiting time constants of the system and, in tests with 40Ca, show that we can reach the desired level of flux in 12 s, with no overshoot. Our results indicate that it may be possible to achieve an even faster response by applying an appropriate one-off heat treatment to the oven before it is used.

Pharmacological prophylaxis against postoperative graft occlusion after peripheral vascular surgery: a world-wide survey.

OBJECTIVES: To define current practice regarding the use of pharmacological prophylaxis to prevent postoperative graft occlusion. DESIGN: Prospective open questionnaire. MATERIALS AND METHODS: Questionnaires regarding this subject were sent to vascular surgeons throughout the world to analyse current practice. RESULTS: 651 questionnaires were returned with a response rate of 62% and form the basis for this report. Data from 100,334 vascular reconstructions were reported in this survey. Prophylaxis against postoperative graft occlusions was common. Treatment periods were usually greater than 1 year. Among carotid surgery patients, 82% received prophylaxis, consisting mainly of low-dose acetysalicylic acid (ASA). In Mid-Europe the use of oral anticoagulation was more common than in other regions (p < 0.001). Among aneurysm surgery patients, 38% received prophylaxis. For infrainguinal bypass, ASA in low dose was the most commonly used agent worldwide. However, oral anticoagulation was more frequent in Mid-Europe, in contrast to South America where the combination of ASA and dipyridamole was most common. Considerable geographical differences regarding patient selection, the frequency of specific procedures and operative techniques existed. CONCLUSIONS: Important world-wide differences exist regarding prophylaxis for postoperative graft occlusion.

Reversal of low-molecular-weight heparin anticoagulation by synthetic protamine analogues.

Protamine reversal of unfractionated and low-molecular-weight heparin (LMWH) causes hypotension, bradycardia, pulmonary artery hypertension, and declines in oxygen consumption. Furthermore, protamine incompletely reverses the anti-Xa activity of LMWH. The present study assesses the efficacy and toxicity of three protamine variants having +16 and +18 charges in reversal of LMWH (Logiparin, LHN-1): [+16] P(AK2A2K2)4, [+18] PK(K2A2K2A)3K2AK3, and [+18B] acetyl-PA(K2A2K2A)4K2-amide. The [+18B] compound was made by acetylating and amidating the [+18] to decrease in vivo degradation and to increase the alpha-helix forming propensity. Variants were examined in a canine model (n = 7, each variant) and compared to controls (n = 7, each variant) and compared to controls (n = 7) reversed with standard protamine with a +21 charge. Animals were anesthetized, anticoagulated with LMWH (150 IU factor Xa activity/kg), and reversed with protamine variants (1.5 mg/kg with 100 IU/mg). Blood pressure (BP), heart rate (HR), cardiac output (CO), pulmonary artery pressures, oxygen saturations, and oxygen consumption (VO2) were continuously monitored. Comparisons were undertaken at baseline, after heparin, before variant administration, and for 30 min thereafter. A total toxicity score (TTS) was calculated for each variant, accounting for maximal declines in BP, HR, CO, and VO2 during the first 5 min after reversal. Protamine [+21] was most toxic, TTS -7.6, with the variants being less toxic (P < 0.01, ANOVA): TTS = [+16] -2.8, [+18] -1.3, and [+18B] -4.1.(ABSTRACT TRUNCATED AT 250 WORDS)

Heparin and protamine use in peripheral vascular surgery: a comparison between surgeons of the Society for Vascular Surgery and the European Society for Vascular Surgery.

It was the intent of this study to document, in general, the patterns and complications of heparin and protamine usage during carotid endarterectomy, aortic and femoral-popliteal-tibial reconstructions for occlusive disease, elective and emergent abdominal aortic aneurysmectomy, thromboembolectomy, and dialysis arteriovenous (AV) fistula placement by surgeons from North America and Europe. All vascular surgeons from the Society for Vascular Surgery (SVS) and the European Society for Vascular Surgery (ESVS) were surveyed by a voluntary, self-reported questionnaire. Six hundred and forty-six completed questionnaires (284 from SVS and 362 from ESVS), representing a 62% response rate, were returned for evaluation. Systemic and regional administration of heparin was common during vascular procedures performed by both SVS and ESVS surgeons. Use of protamine to reverse heparin anticoagulation varied among SVS and ESVS surgeons, respectively, during: carotid endarterectomy (54% vs. 26%, p < 0.01), elective aortic reconstruction for occlusive disease (58% vs. 23%, p < 0.001), elective aortic reconstruction for abdominal aortic aneurysm (63% vs. 27%, p < 0.001), and femoral-popliteal-tibial reconstruction (44% vs. 15%, p < 0.001). Adverse reactions to protamine among the 25,219 and 12,902 cases reported from SVS and ESVS surgeons, respectively, included: hypotension (1209 and 495 cases), pulmonary artery hypertension (65 and eight cases), anaphylaxis (52 and 10 cases), and death (seven and two cases). These adverse responses accounted for 5.3% and 4.0% of the SVS and ESVS cases, respectively. Although this study is subject to the known limitations of a retrospective survey, it is clear that heparin use is common. Protamine reversal of heparin anticoagulation is more common in North America.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy and toxicity of differently charged polycationic protamine-like peptides for heparin anticoagulation reversal.

PURPOSE: The role of total cationic charge of synthetic protamine-like peptides in heparin anticoagulation reversal and accompanying adverse hemodynamic effects was studied. METHODS: Five protamine variants having specific total charges of [+8], [+16], [+18], [+20], and [+21] were synthesized by fluorenylmethoxycarbonyl procedures. Each of these lysine-containing peptides plus arginine-containing control salmine native protamine (n-protamine, [+21] charge) was studied in five dogs who received heparin 150 IU/kg intravenously followed by 1.5 mg/kg (intravenously during a 10-second period) of the synthesized peptide or control n-protamine. RESULTS: Anticoagulation reversal as assessed by a number of coagulation tests was more effective with peptides of greater cationic charge. In this regard, activated clotting time reversal 3 minutes after peptide administration was 7%, [+8]; 54%, [+16]; 81%, [+18]; 92%, [+20]; 81%, [+21]; and greater than 100% [n-protamine]. Reversal of heparin anticoagulation at 3 and 30 minutes, respectively, correlated significantly (*p < or = 0.05, p < or = 0.01 [see corresponding symbols within abstract]) with total cationic charge as assessed by activated clotting time (r = 0.97, 0.99 ), prothrombin time (r = 0.98, 0.87*), activated partial thromboplastin time (r = 0.99, 0.78), thrombin clotting time (r = 0.84,* 0.85*), heparin anti-Xa activity (r = 0.87,* 0.85*), and heparin anti-IIa activity (r = 0.79 at 3 minutes, p = 0.06). Maximum declines in systemic mean arterial pressure (MAP) were greater with more positively charged peptides: -1 mm Hg, [+8]; -3 mm Hg, [+16]; -31 mm Hg; [+18]; -31 mm Hg, [+20]; -35 mm Hg, [+21]; and -34 mm Hg [n-protamine]. Maximum decreases in MAP, cardiac output, and systemic oxygen consumption were highly correlated (p < or = 0.05) with total cationic charge: MAP, r = 0.87; cardiac output, r = 0.87; and systemic oxygen consumption, r = 0.86. A total toxicity score, reflecting adverse hemodynamic effects, was greater with increasing charge: -1.9 +/- 1.1, [+8]; -2.7 +/- 0.8, [+16]; -6.6 +/- 3.3, [+18]; -6.1 +/- 3.5, [+20]; -6.9 +/- 3.8, [+21]; and -7.0 +/- 5.2 [n-protamine]. The correlation of mean peptide total toxicity score to total cationic charge was significant (r = 0.89, p < 0.05). CONCLUSIONS: These data suggest for the first time that effective alternatives to salmine protamine for reversal of heparin anticoagulation can be synthesized. Furthermore, total cationic charge appears to be an important determinant for both anticoagulation reversal and toxicity of protamine-like peptides.

The Effects of Aluminum on the Influx of Calcium, Potassium, Ammonium, Nitrate, and Phosphate in an Aluminum-Sensitive Cultivar of Barley (Hordeum vulgare L.).

The mechanism by which aluminum interferes with ion influx is not known. In this study, the effects of aluminum on the influx of the cations calcium, potassium, and ammonium and the anions nitrate and phosphate were measured in an aluminum-sensitive cultivar of barley (Hordeum vulgare L.). Aluminum (100 [mu]M) was found to inhibit the influx of the cations calcium (69%), ammonium (40%), and potassium (13%) and enhancing the influx of the anions nitrate (44%) and phosphate (17%). Aluminum interfered with the binding of the cations in the cell wall by the same order of magnitude as their respective influxes, whereas phosphate binding was strongly enhanced. The results are consistent with a mechanism whereby aluminum binds to the plasma membrane phospholipids, forming a positively charged layer that influences ion movement to the binding sites of the transport proteins. A positive charge layer would retard the movement of cations and increase the movement of anions to the plasma membrane in proportion to the charges carried by these ions.

Soft Boston orthosis in management of neuromuscular scoliosis: a preliminary report.

Collapsing neuromuscular spinal curvature is extremely difficult to manage with standard rigid orthoses owing to skin breakdown and patient intolerance. Experience with a new, more malleable type of spinal brace (the "soft Boston orthosis") has been very rewarding in 55 children with neuromuscular scoliosis with an average curvature of 42 degrees. Patient tolerance was improved in 38%, patient handling was facilitated in 68%, and postural positioning was enhanced in 79%. Although improvement in the scoliosis averaged only 15 degrees, the major advantage of this orthosis was a marked improvement in sitting stability in 80% of patients.

Heparin-mediated reductions of the toxic effects of protamine sulfate on rabbit myocardium.

Protamine sulfate causes direct myocardial suppression when used to reverse heparin anticoagulation. Protamine's excessive positive charge accompanying its surface arginine groups appears to be responsible for this toxicity. This study was designed to assess the hypothesis that negatively charged heparin given after protamine exposure may enhance the recovery of protamine-induced myocardial dysfunction. Isolated rabbit hearts (n = 20) were perfused with physiologic saline solution at 80 to 90 mm Hg containing high dose protamine, 250 micrograms/ml, until heart contraction essentially ceased (baseline). Hearts were then randomly reperfused for 15 minutes with either physiologic saline solution (group I, n = 10) or heparin plus physiologic saline solution (group II, n = 10) at a dose of 0.1 IU/1.0 microgram of previously administered protamine. Developed left ventricular blood pressure, heart rate, pulmonary artery PaO2, contractility (+dp/dt), oxygen extraction (AvO2), oxygen consumption (VO2), and rate x pressure product were assessed. A protective, beneficial response accompanied heparin administration (group II) in all functions assessed except blood pressure. Maximum changes, comparing group I with II, were heart rate (beats/min) -72 versus -1, p less than 0.001; +dp/dt -64% versus -51%, p less than 0.01; PaO2 +86% versus +9%, p less than 0.001; AvO2 -37% versus -4%, p less than 0.001; VO2 -50% versus -28%, p less than 0.008; and rate x pressure product -73% versus -51%, p less than 0.001. These data suggest a separation of protamine's hemodynamic effects (blood pressure) and metabolic effects (VO2). Furthermore, these data support the tenet that heparin is able to markedly lessen the toxic myocardial effects of protamine.

Sodium homeostasis in term and preterm neonates. III. Effect of salt supplementation.

Clinical and biochemical effects of supplementing dietary sodium intake to 4 to 5 mmol(mEq)/kg/day from days 4 to 14 of life were studied in 22 infants of gestational age 27 to 34 weeks. These infants were compared with a group of 24 unsupplemented babies. Supplemented infants lost less weight postnatally and regained birthweight more quickly: their improved weight gain continued after supplementation was stopped. Sodium balance was positive at age 5 to 11 days in supplemented babies but slightly negative in controls. Potassium balance was more strongly positive in the supplemented group. Plasma sodium concentration was higher in supplemented infants during weeks 3 and 4. Hyponatraemia was significantly more common in unsupplemented (37.5%) than supplemented (13.6%) infants. No infant became oedematous, hypernatraemic, or showed evidence of circulatory overload. The incidence of patent ductus arteriosus and necrotising enterocolitis was not increased; no intracranial haemorrhages occurred. Urinary potassium:sodium ratio was lower in supplemented babies than controls suggesting responsiveness of the distal tubule to mineralocorticoids. Providing 4 to 5 mmol(mEq)/kg/day of sodium to infants born before 34 weeks' gestation for the first two postnatal weeks improves growth and biochemical status and causes no undesirable side effects.

Diagnostic ultrasound in the assessment of patients with incompetent cervix.

Twenty-five pregnant women with suspected cervical incompetence were assessed by serial ultrasound. A dilating internal os was documented in one patient, incompetence was ruled out in two, and a 'slipping suture' was demonstrated in another; the remaining patients were subjected to cerclage on the basis of their history alone. Patients in whom the diagnosis of cervical incompetence is indefinite should have a diagnostic ultrasound scan to visualize the cervix for length, opening of the canal and integrity of the internal os. Selective ultrasonography may be beneficial in both the diagnosis and treatment of cervical incompetence.

Antenatal diagnosis of twin transfusion syndrome by ultrasound.

The evaluation of 2 cases of twin transfusion syndrome by conventional and real-time B-scan ultrasound is described. The importance of differentiating this syndrome from the isolated growth failure of 1 fetus in a twin pregnancy with a normally developing second fetus is emphasized. Assessment of placentation, fetal size and activity, as well as amount of fluid by diagnostic ultrasound is an important aid in the management of multiple gestation.