Generalized scaling of spin qubit coherence in over 12,000 host materials.

SignificanceAtomic defects in solid-state materials are promising candidates as quantum bits, or qubits. New materials are actively being investigated as hosts for new defect qubits; however, there are no unifying guidelines that can quantitatively predict qubit performance in a new material. One of the most critical property of qubits is their quantum coherence. While cluster correlation expansion (CCE) techniques are useful to simulate the coherence of electron spins in defects, they are computationally expensive to investigate broad classes of stable materials. Using CCE simulations, we reveal a general scaling relation between the electron spin coherence time and the properties of qubit host materials that enables rapid and quantitative exploration of new materials hosting spin defects.

Entanglement and control of single nuclear spins in isotopically engineered silicon carbide.

Nuclear spins in the solid state are both a cause of decoherence and a valuable resource for spin qubits. In this work, we demonstrate control of isolated 29Si nuclear spins in silicon carbide (SiC) to create an entangled state between an optically active divacancy spin and a strongly coupled nuclear register. We then show how isotopic engineering of SiC unlocks control of single weakly coupled nuclear spins and present an ab initio method to predict the optimal isotopic fraction that maximizes the number of usable nuclear memories. We bolster these results by reporting high-fidelity electron spin control (F = 99.984(1)%), alongside extended coherence times (Hahn-echo T2 = 2.3 ms, dynamical decoupling T2DD > 14.5 ms), and a >40-fold increase in Ramsey spin dephasing time (T2*) from isotopic purification. Overall, this work underlines the importance of controlling the nuclear environment in solid-state systems and links single photon emitters with nuclear registers in an industrially scalable material.

Purcell Enhancement of a Single Silicon Carbide Color Center with Coherent Spin Control.

Silicon carbide has recently been developed as a platform for optically addressable spin defects. In particular, the neutral divacancy in the 4H polytype displays an optically addressable spin-1 ground state and near-infrared optical emission. Here, we present the Purcell enhancement of a single neutral divacancy coupled to a photonic crystal cavity. We utilize a combination of nanolithographic techniques and a dopant-selective photoelectrochemical etch to produce suspended cavities with quality factors exceeding 5000. Subsequent coupling to a single divacancy leads to a Purcell factor of ∼50, which manifests as increased photoluminescence into the zero-phonon line and a shortened excited-state lifetime. Additionally, we measure coherent control of the divacancy ground-state spin inside the cavity nanostructure and demonstrate extended coherence through dynamical decoupling. This spin-cavity system represents an advance toward scalable long-distance entanglement protocols using silicon carbide that require the interference of indistinguishable photons from spatially separated single qubits.

A large-scale complex haploinsufficiency-based genetic interaction screen in Candida albicans: analysis of the RAM network during morphogenesis.

The morphogenetic transition between yeast and filamentous forms of the human fungal pathogen Candida albicans is regulated by a variety of signaling pathways. How these pathways interact to orchestrate morphogenesis, however, has not been as well characterized. To address this question and to identify genes that interact with the Regulation of Ace2 and Morphogenesis (RAM) pathway during filamentation, we report the first large-scale genetic interaction screen in C. albicans.Our strategy for this screen was based on the concept of complex haploinsufficiency (CHI). A heterozygous mutant of CBK1(cbk1Δ/CBK1), a key RAM pathway protein kinase, was subjected to transposon-mediated, insertional mutagenesis. The resulting double heterozygous mutants (6,528 independent strains) were screened for decreased filamentation on SpiderMedium (SM). From the 441 mutants showing altered filamentation, 139 transposon insertion sites were sequenced,yielding 41 unique CBK1-interacting genes. This gene set was enriched in transcriptional targets of Ace2 and, strikingly, the cAMP-dependent protein kinase A (PKA) pathway, suggesting an interaction between these two pathways. Further analysis indicates that the RAM and PKA pathways co-regulate a common set of genes during morphogenesis and that hyperactivation of the PKA pathway may compensate for loss of RAM pathway function. Our data also indicate that the PKA­regulated transcription factor Efg1 primarily localizes to yeast phase cells while the RAM­pathway regulated transcription factor Ace2 localizes to daughter nuclei of filamentous cells, suggesting that Efg1 and Ace2 regulate a common set of genes at separate stages of morphogenesis. Taken together, our observations indicate that CHI­based screening is a useful approach to genetic interaction analysis in C. albicans and support a model in which these two pathways regulate a common set of genes at different stages of filamentation.

Emergency department patient knowledge and physician communication regarding CT scans.

OBJECTIVES: This study evaluated several aspects of patients' and providers' knowledge and attitude regarding emergency CT scan use. Specifically, is patient awareness of radiation risks changing over time and do levels of education affect this knowledge? Meanwhile, do emergency medicine providers discuss risks with patients and do patients want to know about these risks? METHODS: We conducted a survey of clinically stable patients in the emergency department (ED) after undergoing a CT scan. RESULTS: 200 patients were surveyed. 82 (41%) were aware that CT scans are associated with radiation exposure. 50 (25%) patients were aware that radiation from CT can increase overall lifetime risk of cancer compared with only 2/76 (3%) conducted in 2002. 29 (14.5%) providers specifically discussed radiation risk with patients prior to the CT. There was a significant trend towards knowledge that CT uses x-rays among those with more education. However, there was no association between level of education and knowledge of cancer risk associated with radiation risk from CT. 82 (41%) would have liked more information regarding radiation risks from the provider. CONCLUSIONS: ED patient knowledge has increased significantly over the past 8 years. At the same time, there is a trend towards ED providers more commonly discussing these risks. Level of education is associated with knowledge that CT uses x-rays, but not with knowledge that this is associated with a greater risk of cancer. Patients often want to be informed of these risks.

Value and limitations of transpulmonary pressure calculations during intra-abdominal hypertension.

OBJECTIVE: To clarify the effect of progressively increasing intra-abdominal pressure on esophageal pressure, transpulmonary pressure, and functional residual capacity. DESIGN: Controlled application of increased intra-abdominal pressure at two positive end-expiratory pressure levels (1 and 10 cm H2O) in an anesthetized porcine model of controlled ventilation. SETTING: Large animal laboratory of a university-affiliated hospital. SUBJECTS: Eleven deeply anesthetized swine (weight 46.2 ± 6.2 kg). INTERVENTIONS: Air-regulated intra-abdominal hypertension (0-25 mm Hg). MEASUREMENTS: Esophageal pressure, tidal compliance, bladder pressure, and end-expiratory lung aeration by gas dilution. MAIN RESULTS: Functional residual capacity was significantly reduced by increasing intra-abdominal pressure at both positive end-expiratory pressure levels (p ≤ 0.0001) without corresponding changes of end-expiratory esophageal pressure. Above intra-abdominal pressure 5 mm Hg, plateau airway pressure increased linearly by ~ 50% of the applied intra-abdominal pressure value, associated with commensurate changes of esophageal pressure. With tidal volume held constant, negligible changes occurred in transpulmonary pressure due to intra-abdominal pressure. Driving pressures calculated from airway pressures alone (plateau airway pressure--positive end-expiratory pressure) did not equate to those computed from transpulmonary pressure (tidal changes in transpulmonary pressure). Increasing positive end-expiratory pressure shifted the predominantly negative end-expiratory transpulmonary pressure at positive end-expiratory pressure 1 cm H2O (mean -3.5 ± 0.4 cm H2O) into the positive range at positive end-expiratory pressure 10 cm H2O (mean 0.58 ± 1.2 cm H2O). CONCLUSIONS: Despite its insensitivity to changes in functional residual capacity, measuring transpulmonary pressure may be helpful in explaining how different levels of positive end-expiratory pressure influence recruitment and collapse during tidal ventilation in the presence of increased intra-abdominal pressure and in calculating true transpulmonary driving pressure (tidal changes of transpulmonary pressure). Traditional interpretations of respiratory mechanics based on unmodified airway pressure were misleading regarding lung behavior in this setting.

Enhancing long-term weight loss maintenance: 2 year results from the Keep It Off randomized controlled trial.

OBJECTIVE: The Keep It Off trial evaluated the efficacy of a phone-based weight loss maintenance intervention among adults who had recently lost weight in Minnesota (2007-2010). METHODS: 419 adults who had recently lost ≥ 10% of their body weight were randomized to the "Guided" or "Self-Directed" intervention. Guided participants received a 10 session workbook, 10 biweekly, eight monthly and six bimonthly phone coaching calls, bimonthly weight graphs and tailored letters based on self-reported weights. Self-Directed participants received the workbook and two calls. Primary outcomes are weight change and maintenance (regain of <2.5% of baseline body weight). RESULTS: Mixed model repeated-measures analysis examining weight change revealed a significant time by treatment group interaction (p<0.0085). Guided participants regained significantly less weight than the Self-Directed participants at 12 and 24 months. The odds of 24 month maintenance were 1.37 (95% CI: 0.97-2.03) times greater in the Guided than in the Self-Directed group. When maintenance rates were compared across all follow-ups, there was a consistently higher maintenance rate for Guided participants (HR 1.31, 95% CI: 1.12-1.54). CONCLUSIONS: A sustained, supportive phone- and mail-based intervention promotes weight loss maintenance relative to a brief intervention for participants who have recently lost weight.

Solvent dependent branching between C-I and C-Br bond cleavage following 266 nm excitation of CH2BrI.

It is well known that ultraviolet photoexcitation of halomethanes results in halogen-carbon bond cleavage. Each halogen-carbon bond has a dominant ultraviolet (UV) absorption that promotes an electron from a nonbonding halogen orbital (nX) to a carbon-halogen antibonding orbital (σ*C-X). UV absorption into specific transitions in the gas phase results primarily in selective cleavage of the corresponding carbon-halogen bond. In the present work, broadband ultrafast UV-visible transient absorption studies of CH2BrI reveal a more complex photochemistry in solution. Transient absorption spectra are reported spanning the range from 275 nm to 750 nm and 300 fs to 3 ns following excitation of CH2BrI at 266 nm in acetonitrile, 2-butanol, and cyclohexane. Channels involving formation of CH2Br + I radical pairs, iso-CH2Br-I, and iso-CH2I-Br are identified. The solvent environment has a significant influence on the branching ratios, and on the formation and stability of iso-CH2Br-I. Both iso-CH2Br-I and iso-CH2I-Br are observed in cyclohexane with a ratio of ~2.8:1. In acetonitrile this ratio is 7:1 or larger. The observation of formation of iso-CH2I-Br photoproduct as well as iso-CH2Br-I following 266 nm excitation is a novel result that suggests complexity in the dissociation mechanism. We also report a solvent and concentration dependent lifetime of iso-CH2Br-I. At low concentrations the lifetime is >4 ns in acetonitrile, 1.9 ns in 2-butanol and ~1.4 ns in cyclohexane. These lifetimes decrease with higher initial concentrations of CH2BrI. The concentration dependence highlights the role that intermolecular interactions can play in the quenching of unstable isomers of dihalomethanes.

Laboratory-confirmed gonorrhea and/or chlamydia rates in clinically diagnosed pelvic inflammatory disease and cervicitis.

OBJECTIVE: The aim of this study was to determine the rates of laboratory confirmed gonorrhea (GC) and chlamydia (CT) in emergency department (ED) patients with pelvic inflammatory disease (PID) and cervicitis who were diagnosed clinically and treated empirically. A secondary goal examines which clinical criteria were present in patients with PID testing positive for GC/CT. METHODS: We conducted a retrospective chart review of all ED patents diagnosed with PID or cervicitis during a 40-month period (January 2007-March 2010). Charts were reviewed for laboratory-confirmed GC or CT. For patients with positive GC or CT studies, the presence of key clinical criteria used in the diagnosis of PID was tallied. RESULTS: A total of 1469 patients were diagnosed with cervicitis and 343 with PID. Of these patients, 27 (1.8%) of 1469 and 15 (4.4%) of 343 were GC positive, and 136 (9.3%) of 1469 and 34 (10%) of 343 were CT positive. Twenty-six cervicitis (1.8%) and 9 PID (2.6%) patients were positive for both infections. One hundred eighty-nine cervicitis (13%) and 58 PID (17%) patients were positive for at least 1 sexually transmitted infection. Of the 58 patients with PID with laboratory-confirmed GC/CT, the following clinical criteria were present: abdominal pain, 58 of 58; abdominal tenderness, 50 of 58; cervical discharge, 47 of 58; cervical motion tenderness, 46 of 58; adnexal tenderness, 32 of 58; vaginal bleeding, 8 of 58; and fever, 2 of 58. Ultrasound was preformed in 27 (47%) of 58 GC/CT-positive patients with PID, with findings suggestive of PID in 12 (44%) of 27 ultrasounds. One hundred percent of abnormal ultrasounds were associated with positive GC and/or CT results. CONCLUSION: There is a generally low prevalence of GC and CT in this patient population diagnosed with cervicitis or PID. There is a very low prevalence of coinfection.

Five-second coherence of a single spin with single-shot readout in silicon carbide.

An outstanding hurdle for defect spin qubits in silicon carbide (SiC) is single-shot readout, a deterministic measurement of the quantum state. Here, we demonstrate single-shot readout of single defects in SiC via spin-to-charge conversion, whereby the defect's spin state is mapped onto a long-lived charge state. With this technique, we achieve over 80% readout fidelity without pre- or postselection, resulting in a high signal-to-noise ratio that enables us to measure long spin coherence times. Combined with pulsed dynamical decoupling sequences in an isotopically purified host material, we report single-spin T2 > 5 seconds, over two orders of magnitude greater than previously reported in this system. The mapping of these coherent spin states onto single charges unlocks both single-shot readout for scalable quantum nodes and opportunities for electrical readout via integration with semiconductor devices.

Barriers in identification and referral to genetic counseling for familial cancer risk: the perspective of genetic service providers.

The purpose of this study was to obtain genetic counselors' perspectives about the identification of appropriate patients and barriers to referral of high-risk patients for cancer genetic counseling services. Genetic service providers from eight integrated health systems were surveyed. Data analysis included descriptive statistics. Twenty-eight of 40 potential participants responded (70%). Referrals for familial cancer risk assessment overwhelmingly came from providers (89%); only 10% were self-referrals. Use of guidelines to assist providers with referral was reported by 46% of the respondents. Genetic service providers perceived patient barriers to seeking genetic counseling after referral included: risk evaluation viewed as a non-priority (72%), concerns about impact on insurability (52%), distance to appointments (48%), lack of insurance (44%), lack of patient/provider knowledge about the value of genetic counseling (36%), discouragement by family members (28%), and fear (20%). The best approaches suggested by respondents to increase appropriate referrals were attending meetings and giving presentations to oncologists, surgeons, primary care and gynecologists. The genetic service providers reported several barriers to the referral and use of genetic counseling. This finding is consistent with current literature from the providers' perspective. Our survey adds the genetic service providers' perspective and identifies areas of opportunity for further research and intervention as few of the perceived barriers are being addressed through current educational efforts.

Vanadium spin qubits as telecom quantum emitters in silicon carbide.

Solid-state quantum emitters with spin registers are promising platforms for quantum communication, yet few emit in the narrow telecom band necessary for low-loss fiber networks. Here, we create and isolate near-surface single vanadium dopants in silicon carbide (SiC) with stable and narrow emission in the O band, with brightness allowing cavity-free detection in a wafer-scale material. In vanadium ensembles, we characterize the complex d 1 orbital physics in all five available sites in 4H-SiC and 6H-SiC. The optical transitions are sensitive to mass shifts from local silicon and carbon isotopes, enabling optically resolved nuclear spin registers. Optically detected magnetic resonance in the ground and excited orbital states reveals a variety of hyperfine interactions with the vanadium nuclear spin and clock transitions for quantum memories. Last, we demonstrate coherent quantum control of the spin state. These results provide a path for telecom emitters in the solid state for quantum applications.

Universal coherence protection in a solid-state spin qubit.

Decoherence limits the physical realization of qubits, and its mitigation is critical for the development of quantum science and technology. We construct a robust qubit embedded in a decoherence-protected subspace, obtained by applying microwave dressing to a clock transition of the ground-state electron spin of a silicon carbide divacancy defect. The qubit is universally protected from magnetic, electric, and temperature fluctuations, which account for nearly all relevant decoherence channels in the solid state. This culminates in an increase of the qubit's inhomogeneous dephasing time by more than four orders of magnitude (to >22 milliseconds), while its Hahn-echo coherence time approaches 64 milliseconds. Requiring few key platform-independent components, this result suggests that substantial coherence improvements can be achieved in a wide selection of quantum architectures.

Systolic Stretch Characterizes the Electromechanical Substrate Responsive to Cardiac Resynchronization Therapy.

OBJECTIVES: In this study, the authors tested the hypotheses that the systolic stretch index (SSI) developed by computer modeling and applied using echocardiographic strain imaging may characterize the electromechanical substrate predictive of outcome following cardiac resynchronization therapy (CRT). They included patients with QRS width 120 to 149 ms or non-left bundle branch block (LBBB), where clinical uncertainty for CRT exists. They further tested the hypothesis that global longitudinal strain (GLS) has additional prognostic value. BACKGROUND: Response to CRT is variable. Guidelines favor patient selection by electrocardiographic LBBB with QRS width ≥150 ms. METHODS: The authors studied 442 patients enrolled in the Adaptive CRT 94-site randomized trial with New York Heart Association functional class III-IV heart failure, ejection fraction ≤35%, and QRS ≥120 ms. A novel computer program semiautomatically calculated the SSI from strain curves as the sum of posterolateral prestretch percent before aortic valve opening and the septal rebound stretch percent during ejection. The primary endpoint was hospitalization for heart failure (HF) or death, and the secondary endpoint was death over 2 years after CRT. RESULTS: In all patients, high longitudinal SSI (≥ group median of 3.1%) was significantly associated with freedom from the primary endpoint of HF hospitalization or death (hazard ratio [HR] for low SSI: 2.17; 95% confidence interval [CI]: 1.45 to 3.24, p < 0.001) and secondary endpoint of death (HR for low SSI: 4.06; 95% CI: 1.95 to 8.45, p < 0.001). Among the 203 patients with QRS 120 to 149 ms or non-LBBB, those with high longitudinal SSI (≥ group median of 2.6%) had significantly fewer HF hospitalizations or deaths (HR for low SSI: 2.08; 95% CI: 1.27 to 3.41, p = 0.004) and longer survival (HR for low SSI: 5.08; 95% CI: 1.94 to 13.31, p < 0.001), similar to patients with LBBB ≥150 ms. SSI by circumferential strain had similar associations with clinical outcomes, and GLS was additive to SSI in predicting clinical events (p = 0.001). CONCLUSIONS: Systolic stretch by strain imaging characterized the myocardial substrate associated with favorable CRT response, including in the important patient subgroup with QRS width 120 to 149 ms or non-LBBB. GLS had additive prognostic value.

Electrical and optical control of single spins integrated in scalable semiconductor devices.

Spin defects in silicon carbide have the advantage of exceptional electron spin coherence combined with a near-infrared spin-photon interface, all in a material amenable to modern semiconductor fabrication. Leveraging these advantages, we integrated highly coherent single neutral divacancy spins in commercially available p-i-n structures and fabricated diodes to modulate the local electrical environment of the defects. These devices enable deterministic charge-state control and broad Stark-shift tuning exceeding 850 gigahertz. We show that charge depletion results in a narrowing of the optical linewidths by more than 50-fold, approaching the lifetime limit. These results demonstrate a method for mitigating the ubiquitous problem of spectral diffusion in solid-state emitters by engineering the electrical environment while using classical semiconductor devices to control scalable, spin-based quantum systems.

Electrically driven optical interferometry with spins in silicon carbide.

Interfacing solid-state defect electron spins to other quantum systems is an ongoing challenge. The ground-state spin's weak coupling to its environment not only bestows excellent coherence properties but also limits desired drive fields. The excited-state orbitals of these electrons, however, can exhibit stronger coupling to phononic and electric fields. Here, we demonstrate electrically driven coherent quantum interference in the optical transition of single, basally oriented divacancies in commercially available 4H silicon carbide. By applying microwave frequency electric fields, we coherently drive the divacancy's excited-state orbitals and induce Landau-Zener-Stückelberg interference fringes in the resonant optical absorption spectrum. In addition, we find remarkably coherent optical and spin subsystems enabled by the basal divacancy's symmetry. These properties establish divacancies as strong candidates for quantum communication and hybrid system applications, where simultaneous control over optical and spin degrees of freedom is paramount.

Optical charge state control of spin defects in 4H-SiC.

Defects in silicon carbide (SiC) have emerged as a favorable platform for optically active spin-based quantum technologies. Spin qubits exist in specific charge states of these defects, where the ability to control these states can provide enhanced spin-dependent readout and long-term charge stability. We investigate this charge state control for two major spin qubits in 4H-SiC, the divacancy and silicon vacancy, obtaining bidirectional optical charge conversion between the bright and dark states of these defects. We measure increased photoluminescence from divacancy ensembles by up to three orders of magnitude using near-ultraviolet excitation, depending on the substrate, and without degrading the electron spin coherence time. This charge conversion remains stable for hours at cryogenic temperatures, allowing spatial and persistent patterning of the charge state populations. We develop a comprehensive model of the defects and optical processes involved, offering a strong basis to improve material design and to develop quantum applications in SiC.

Control of Hydroid Colony Form by Surface Heterogeneity.

The colonial hydroid Podocoryna carnea grows adherent to surfaces progressing along them by a motile stolon tip. We here ask whether the stolon tip grows preferentially within grooves etched in silicon wafers. In a series of pilot experiments, we varied the dimensions of grooves and found that stolons did not utilize grooves with a width:depth of 5:5 µm or 10:10 µm, occasionally followed grooves 25:25 µm in size, and preferentially grew within grooves of a width:depth of 50:50 µm and 100:50 µm. We then grew colonies in grids, with fixed 50:50 µm width:depth channels intersecting at 90° every 950, 700, 450, or 150 µm. We find that stolons grew within grooves early in colony ontogeny, but remained restricted to them only in the grid pattern with channel intersections every 150 µm. Finally, we created a grid in the shape of the Yale Y logo, with channels of 50:50 µm width:depth and intersections every 100 µm. The resulting colonies conformed to that of the logo. Our findings demonstrate that stolons respond to surface heterogeneity and that surface etching can be used to fabricate microfluidic circuits comprised of hydroid perisarc.

Use of Intra-arterial Thrombolytic Therapy for Acute Treatment of Frostbite in 62 Patients with Review of Thrombolytic Therapy in Frostbite.

Amputations are common after severe frostbite injuries, often mediated by postinjury arterial thrombosis. Since 1994, the authors have performed angiography to identify perfusion deficits in severely frostbitten digits and treated these lesions with intraarterial infusion of thrombolytic agents, usually combined with papaverine to reduce vasospasm. A retrospective review was performed of patients admitted to the regional burn center with frostbite injury from 1994 to 2007. Patients with severe frostbite, without contraindications to thrombolytic therapy, underwent diagnostic angiography of the affected extremities. Limbs with perfusion defects received intraarterial thrombolytic therapy according to protocol and the response was documented. Delayed amputation was performed for mummified digits. Angiogram results and amputation rates were tabulated. In this 14-year review, 114 patients were admitted for frostbite injuries. There was a male predominance (84%) and the mean age was 40.4 years. Of this group, 69 patients with severe frostbite underwent angiography; 66 were treated with intraarterial thrombolytic therapy. Four treated were excluded due to incomplete data. In the remaining 62 patients, angiography identified 472 digits with frostbite injury and impaired arterial perfusion. At the termination of thrombolytic infusion, a completion angiogram was performed. Partial or complete amputations were performed on only four of 198 digits (2.0%) with distal vascular blush, and in 71 of 75 digits (94.7%) with no improvement. Amputations occurred in 73 of 199 digits (36.7%) with partially restored flow. Overall complete digit salvage rate was 68.6%. Angiography after severe frostbite is a sensitive method to detect impaired arterial blood flow and permits catheter-directed treatment with thrombolytic agents. Improved perfusion after such treatment decreases late amputations following frostbite injury.