Filtering Crosstalk from Bath Non-Markovianity via Spacetime Classical Shadows.

From an open system perspective non-Markovian effects due to a nearby bath or neighboring qubits are dynamically equivalent. However, there is a conceptual distinction to account for: neighboring qubits may be controlled. We combine recent advances in non-Markovian quantum process tomography with the framework of classical shadows to characterize spatiotemporal quantum correlations. Observables here constitute operations applied to the system, where the free operation is the maximally depolarizing channel. Using this as a causal break, we systematically erase causal pathways to narrow down the progenitors of temporal correlations. We show that one application of this is to filter out the effects of crosstalk and probe only non-Markovianity from an inaccessible bath. It also provides a lens on spatiotemporally spreading correlated noise throughout a lattice from common environments. We demonstrate both examples on synthetic data. Owing to the scaling of classical shadows, we can erase arbitrarily many neighboring qubits at no extra cost. Our procedure is thus efficient and amenable to systems even with all-to-all interactions.

Demonstration of non-Markovian process characterisation and control on a quantum processor.

In the scale-up of quantum computers, the framework underpinning fault-tolerance generally relies on the strong assumption that environmental noise affecting qubit logic is uncorrelated (Markovian). However, as physical devices progress well into the complex multi-qubit regime, attention is turning to understanding the appearance and mitigation of correlated - or non-Markovian - noise, which poses a serious challenge to the progression of quantum technology. This error type has previously remained elusive to characterisation techniques. Here, we develop a framework for characterising non-Markovian dynamics in quantum systems and experimentally test it on multi-qubit superconducting quantum devices. Where noisy processes cannot be accounted for using standard Markovian techniques, our reconstruction predicts the behaviour of the devices with an infidelity of 10-3. Our results show this characterisation technique leads to superior quantum control and extension of coherence time by effective decoupling from the non-Markovian environment. This framework, validated by our results, is applicable to any controlled quantum device and offers a significant step towards optimal device operation and noise reduction.

Two-electron spin correlations in precision placed donors in silicon.

Substitutional donor atoms in silicon are promising qubits for quantum computation with extremely long relaxation and dephasing times demonstrated. One of the critical challenges of scaling these systems is determining inter-donor distances to achieve controllable wavefunction overlap while at the same time performing high fidelity spin readout on each qubit. Here we achieve such a device by means of scanning tunnelling microscopy lithography. We measure anti-correlated spin states between two donor-based spin qubits in silicon separated by 16 ± 1 nm. By utilising an asymmetric system with two phosphorus donors at one qubit site and one on the other (2P-1P), we demonstrate that the exchange interaction can be turned on and off via electrical control of two in-plane phosphorus doped detuning gates. We determine the tunnel coupling between the 2P-1P system to be 200 MHz and provide a roadmap for the observation of two-electron coherent exchange oscillations.

A quantum spin-probe molecular microscope.

Imaging the atomic structure of a single biomolecule is an important challenge in the physical biosciences. Whilst existing techniques all rely on averaging over large ensembles of molecules, the single-molecule realm remains unsolved. Here we present a protocol for 3D magnetic resonance imaging of a single molecule using a quantum spin probe acting simultaneously as the magnetic resonance sensor and source of magnetic field gradient. Signals corresponding to specific regions of the molecule's nuclear spin density are encoded on the quantum state of the probe, which is used to produce a 3D image of the molecular structure. Quantum simulations of the protocol applied to the rapamycin molecule (C51H79NO13) show that the hydrogen and carbon substructure can be imaged at the angstrom level using current spin-probe technology. With prospects for scaling to large molecules and/or fast dynamic conformation mapping using spin labels, this method provides a realistic pathway for single-molecule microscopy.

Preference and satisfaction with a 6-month subcutaneous injection versus a weekly tablet for treatment of low bone mass.

UNLABELLED: The Preference and Satisfaction Questionnaire (PSQ) compares patient preference and satisfaction between a 6-month subcutaneous injection and weekly oral tablet for treatment of bone loss. Patients preferred and were more satisfied with a treatment that was administered less frequently, suggesting the acceptability of the 6-month injection for treatment of bone loss. INTRODUCTION: The PSQ compares patient preference and satisfaction between a 6-month subcutaneous injection and a weekly oral tablet for treatment of bone loss. METHODS: Postmenopausal women with low bone mass who enrolled in two separate randomized phase 3 double-blind, double-dummy studies received a 6-month subcutaneous denosumab injection (60 mg) plus a weekly oral placebo or a weekly alendronate tablet (70 mg) plus a 6-month subcutaneous placebo injection. After 12 months, patients completed the PSQ to rate their preference, satisfaction, and degree of bother with each regimen. RESULTS: Most enrolled patients (1,583 out of 1,693; 93.5%) answered >or=1 item of the PSQ. Significantly more patients preferred and were more satisfied with the 6-month injection versus the weekly tablet (P < 0.001). More patients reported no bother with the 6-month injection (90%) than the weekly tablet (62%). CONCLUSION: Patients preferred, were more satisfied, and less bothered with a 6-month injection regimen for osteoporosis.

Sensing of fluctuating nanoscale magnetic fields using nitrogen-vacancy centers in diamond.

New magnetometry techniques based on nitrogen-vacancy (NV) defects in diamond allow for the detection of static (dc) and oscillatory (ac) nanoscopic magnetic fields, yet are limited in their ability to detect fields arising from randomly fluctuating (FC) environments. We show here that FC fields restrict dc and ac sensitivities and that probing the NV dephasing rate in a FC environment should permit the characterization of FC fields inaccessible to dc and ac techniques. FC sensitivities are shown to be comparable to those of ac magnetometry and require no additional experimental overhead or sample control.

Descriptive epidemiology of injury and illness among cruise ship passengers.

STUDY OBJECTIVE: To provide information, which can be used in the formation of guidelines concerning medical facilities and staff on cruise ships, on the descriptive epidemiology of the medical conditions encountered by cruise ship physicians. METHODS: A retrospective descriptive epidemiologic study design was used to evaluate patient physician encounters on cruises originating in a calendar-year period for the 4 ships of a major cruise ship line with cruises originating in the United States. Demographic data regarding sex and age of the passengers on these ships were available for each cruise. We collected information on patient age, sex, chief complaint, diagnoses, treatment, and patient disposition recorded in the patients' medical records in the ships' medical logs. RESULTS: Seven thousand one hundred forty-seven new patient visits occurred in a population of 196,171 passengers and 1,537,298 passenger days; 56.7% of passengers were female, and 60.7% of patients were female; 43.3% of passengers and 39.6% of patients were male. Visits to the ship infirmaries were made for the following reasons: 18.2% of visits were related to injuries, 69.3% were related to medical conditions, and 12.5% were unspecified or other conditions. The most common diagnosis was respiratory tract infection (29.1%); 11% of patients had a serious or potentially life-threatening diagnosis. The most common group of prescription medications prescribed was antibiotics. CONCLUSION: Many different injuries and illnesses occur on board cruise ships. The spectrum is similar in many respects to the patients presenting to emergency departments. Cruise lines must prepare for the initial treatment and stabilization of patients with serious illnesses or injuries with appropriately qualified and equipped medical personnel and establish procedures for disembarkation of patients to facilities capable of handling such conditions.

Recovery and relapse in geriatric depression after treatment with antidepressants and ECT in a medical-psychiatric population.

The objective of this naturalistic, longitudinal treatment outcome study was to determine relapse rates in geriatric depression following treatment with antidepressants and electroconvulsive therapy in a medical-psychiatric population. Thirty-nine elderly patients (average age 71 years) with unipolar major depression were treated with either antidepressants (AD) or, if resistant to AD treatment, ECT followed by maintenance antidepressants. Patients were monitored over 18 months, and relapse rates were closely determined using the Longitudinal Interval Follow-up Evaluation (LIFE) and the 21-item Hamilton Depression Rating Scale. Although 90% of patients recovered from their index episode of depression, relapse rates were approximately 29%. These results indicate that in spite of high chances of recovery from geriatric depression, intensive psychopharmacologic and psychotherapeutic strategies are needed to decrease relapse rates in geriatric depression.

Lithium intolerance in a medical-psychiatric population.

This pilot study was designed to explore the tolerance and efficacy of lithium as an adjunctive prophylactic agent when added to maintenance antidepressant regimens following an episode of depression in an older medical-psychiatric population. In a randomized controlled trial, 27 depressed patients had either lithium carbonate or placebo added to their maintenance antidepressant (AD) regimen following an index episode of depression. Of 17 patients who received lithium carbonate, 76% (13/17) were unable to tolerate this agent for the duration of the study because of side effects (e.g., gastrointestinal disturbances or tremor). The four patients who tolerated lithium were monitored for relapse of depression over a 15-month follow-up period, and one relapsed (after a 49-week remission) whereas 60% (6/10) of the placebo patients relapsed. Cognitive functioning was stable in the lithium-treated patients who remained on therapy. The high rate of lithium intolerance in this study indicates that lithium dosing and serum levels must be conservatively managed in this clinical population.

Predicting aggressive and socially disruptive behavior in a maximum security forensic psychiatric hospital.

The predictive utility of Hare, Hart, and Cox's Psychopathy Checklist Screening Version (PCL:SV) was assessed utilizing a sample of forensic psychiatric patients from Vernon State Hospital in Vernon, Texas. A sample of 55 patients were interviewed and rated on the PCL:SV. During a six month follow up, occurrences of self-harm (suicide attempts and self mutilation), aggression (verbal abuse and threats, irritability, belligerence, and fighting) escape potential (threats and attempts), and treatment refusal (medication, tests, and physician's appointments) were rated. Separate stepwise multiple regression analyses were performed utilizing patient's age, type of charges, documented history of alcohol/drug abuse and the PCL:SV as predictor variables. Results indicate that the PCL:SV is predictive of aggression and treatment noncompliance.

Improvement in depression-related cognitive dysfunction following ECT.

Long-term cognitive changes were observed in 8 depressed patients whose pretreatment cognitive impairment (depressive dementia or pseudodementia) resolved after treatment with ECT. Improved performance on the Mattis Dementia Rating Scale was maintained throughout a 4-year follow-up period. Improvements on Memory and Initiation and Perseveration subscales were most consistent over time. These aspects of cognitive functioning may be the most susceptible to the effects of depression, and this may be a factor to consider in clinically evaluating older patients with both depression and cognitive impairment. The findings indicate that elderly patients with cognitive dysfunction secondary to depression may experience improvement in cognitive functioning that is stable over time with remission of the affective disorder.

Rehospitalization rates in older depressed adults after antidepressant and electroconvulsive therapy treatment.

OBJECTIVE: To determine (1) if a "high risk" period for rehospitalization can be identified in a population of depressed older adults and (2) if age of onset and previous history of depression is associated with an increased risk of rehospitalization. DESIGN: Naturalistic, longitudinal treatment outcome study. SETTING: Medical-psychiatry unit and outpatient clinic at a university hospital. PATIENTS: Ninety-four older adults diagnosed with major depression based on SCID and DSM-III-R criteria who were hospitalized for treatment. INTERVENTIONS: All patients were initially hospitalized on a medical-psychiatry unit and treated with either antidepressants or electroconvulsive therapy. MEASUREMENTS: Patients were initially evaluated with the Structured Clinical Interview for DSM-III-R (SCID), the Hamilton Depression Rating Scale, and a battery of neuro-psychological and behavioral tests. Patients were followed over time with an average follow-up interval of 3.09 + 1.45 years, and the date of the first psychiatric rehospitalization (if any) was recorded. RESULTS: Approximately 43.6 percent of the total sample required at least one psychiatric rehospitalization. The greatest risk of rehospitalization occurred in the first 18 months. No significant differences were noted between patient groups treated with ECT and those treated with antidepressants or between patients with a younger and those with an older age of onset of depressive disorder. A statistical trend was observed in which patients without previous episodes of depression had a lower overall rate of rehospitalization compared with patients with one or more previous episodes of depression. CONCLUSIONS: There appears to be a relatively high risk of psychiatric rehospitalization in depressed older adults, particularly in the first 18 months. This rate of rehospitalization underscores the importance of providing maintenance therapy and intensive psychiatric supervision for a minimum of 18 months to 2 years during the course of a depressive episode requiring inpatient hospitalization.

Long-term outcome of treatment-resistant depression in older adults.

Seventeen elderly patients with treatment-resistant depression were reassessed 15 months and 4 years after treatment with an antidepressant agent or ECT. At 15 months 47% (seven of 15) were clinically improved, and at the 4-year follow-up 71% (10 of 14) were improved. These results indicate that treatment-resistant depression may improve over time because of either the natural course of the illness or persistent treatment efforts.

Long-term affective and cognitive outcome in depressed older adults.

OBJECTIVE: The purpose of this naturalistic study was to examine the long-term (15 months and 4 years) cognitive and affective outcome following treatment with either cyclic antidepressants or ECT in depressed older adults. METHOD: Fifty-five patients meeting criteria for major depression were rated as to cognitive impairment and were treated as clinically indicated with either a cyclic antidepressant or ECT. Long-term outcome was determined through psychometric retesting 15 months (N = 47) and approximately 4 years (N = 44) after treatment. RESULTS: Analysis of 15-month and 4-year outcome evaluations revealed that the majority of patients improved over time with respect to their depression, regardless of whether they exhibited pretreatment cognitive impairment or were treated with cyclic antidepressants or ECT. Fifteen months and 4 years after treatment, 72.3% and 83.7% of patients, respectively, exhibited clinically meaningful improvement. However, patients given both cyclic antidepressants and ECT demonstrated a relatively high rate of rehospitalization (50%) over the course of the 4 years. Except for patients who developed dementia, cognitive functioning remained stable or improved for the majority of patients. In patients who received ECT, those with normal pretreatment cognition had stable cognitive functioning over time and those who had pretreatment cognitive dysfunction showed improvement over the 4-year follow-up period. CONCLUSIONS: Results of this study indicate that the long-term prognosis of depression in older adults is generally favorable, although they may be prone to relapse and recurrence, which points to the need for rigorous monitoring and follow-up care.

Similarities and differences in memory deficits in patients with primary dementia and depression-related cognitive dysfunction.

The authors examined differences between the verbal memory performance of older patients with major depression (MD) alone; major depression with reversible depression-related cognitive dysfunction (MD/DRCD); and primary dementia and major depression (DEM/MD). Patients were evaluated before antidepressant treatment and 6 and 15 months after treatment. Of the three groups, patients with MD alone acquired significantly more information on the California Verbal Learning Test and showed a more pronounced primacy effect. Patients with DEM/MD were more likely to commit errors of intrusion. Although older depressed patients with MD/DRCD may resemble patients with DEM/MD on some aspects of verbal memory performance, differences may be observed in the types of learning errors they commit. Diagnostic implications are discussed.

Dysnomia in the differential diagnosis of major depression, depression-related cognitive dysfunction, and dementia.

This study examined naming abilities in three groups of older adults with: I) major depression alone, II) major depression with reversible cognitive dysfunction, and III) dementia with depression. Groups I and II differed significantly from dementia patients in total correct responses to a visual-confrontation naming task (Boston Naming Test). Qualitative aspects of naming, specifically types of errors characterizing each patient group, were examined, but no statistically significant differences among groups were observed. The results support the contention that the presence of dysnomia may be useful in discriminating cognitive abnormalities secondary to dementia from cognitive dysfunction associated with depression.

Cognitive deficits in delirium: assessment over time.

Delirium is commonly defined as a transient organic brain syndrome characterized by concurrent disorders of attention, perception, thinking, memory, psychomotor behavior, and the sleep-wake cycle. One of the difficulties in studying delirium is that symptoms tend to fluctuate over the course of the day. Pre-existing organic brain disease appears to be a significant risk factor for the development of delirium, and numerous studies have shown a high rate of delirium in patients with cerebrovascular disease, Parkinson's disease, and Alzheimer's disease. The cognitive deficits associated with delirium have not been widely studied in a systematic, quantitative fashion. Following resolution of the frank delirium, documented cognitive deficits can be observed, and may persist in a diluted form for a period of months. Residual cognitive deficits may be due to a minimal and persistent confusion or to an underlying brain disorder.

Cognitive outcome following tricyclic and electroconvulsive treatment of major depression in the elderly.

OBJECTIVE: This study sought to ascertain the affective and cognitive outcome after tricyclic and electroconvulsive treatment of elderly medical-psychiatric patients meeting diagnostic criteria for major depression, some of whom had normal cognitive functioning and some of whom were cognitively impaired before treatment. METHOD: Patients who met criteria for major depression on the basis of a structured diagnostic interview and who scored 17 or more on the Hamilton Rating Scale for Depression were evaluated with the Mattis Dementia Rating Scale. The patients were then treated in a nonrandom manner with either tricyclic antidepressants or ECT (followed by tricyclic maintenance therapy). The majority of the patients treated with ECT had not responded previously to tricyclics. Follow-up psychometric testing was repeated in 6 months. RESULTS: Among the patients with normal pretreatment cognitive functioning, cognition was generally stable. Among the patients with pretreatment cognitive impairment, a substantial number--including those receiving ECT--demonstrated improvement in cognition. While the majority of patients improved with respect to both their affective and cognitive states, certain treatment-refractory subgroups were nevertheless identified. CONCLUSIONS: The data suggest that cognitive dysfunction associated with depression may improve after treatment in a substantial number of elderly patients, including those receiving ECT. Relapse rates, however, may be relatively high, and residual symptoms may persist, which emphasizes the need for optimal initial and long-term antidepressant strategies for this population.

Numerical tests of a method for simulating electrical potentials on the cortical surface.

A mathematical imaging method for simulating cortical surface potentials was introduced at recent neurosciences meetings [1a], [1b], [2] and was applied to elucidate the neural origins of evoked responses in normal volunteers and certain patient populations. This method consists of the solution of an inward harmonic continuation problem and its effect is to simulate data that has not been attenuated and smeared by the skull. This cortical imaging technique (CIT) is validated by applying it to artificially derived data. Pairs of dipolar sources with different depths and separations are introduced into a spherical conducting medium simulating the head. Scalp potential maps are constructed by interpolating the simulated data between 28 "scalp" electrode positions. Noise is added to the data to approximate the variability in measured potentials that would be observed in practice. CIT is used in each case to construct potential maps on layers concentric to and within the layer representing the scalp. In several instances when the dipole pair is deep and closely spaced, the sources cannot be separated by the scalp topographical maps but are easily separated by the "cortical" topographical maps. CIT is also applied to scalp-recorded potentials evoked by bilateral median nerve stimulation and pattern-reversal visual stimulation.

The medical-psychiatric unit as a site for outcome research in dementia/depression syndromes.

The era of cross-sectional "snapshot" clinical epidemiology studies in consultation-liaison psychiatry, while still important, do not in themselves yield the critical outcome information needed to document both the clinical efficacy and cost-efficacy of timely psychiatric treatment of patients with concurrent medical-psychiatric illness. As consultation-liaison psychiatry has been plagued by problems regarding reimbursement for clinical services rendered and has only a few systematic outcome studies as yet documenting the effectiveness of treatment interventions, more prospective studies are desperately needed to confirm the value of our efforts. The era of proselytizing the virtues of consultation-liaison psychiatry is over, and as with every other area of psychiatric therapy, governmental policy makers and third party payors are appropriately demanding to see "proof" that our treatments are both clinically- and cost-effective. As may be seen from this brief overview of our research demonstrating the potential reversibility of disabling cognitive dysfunction in depressed medical-psychiatric patients and the efficacy of labetalol in decreasing cardiovascular complications from ECT in high risk medical patients, positive reports from clinical investigations that are strategically planned and implemented on specific populations form strong arguments for the clinical and probable cost efficacy of both consultation-liaison psychiatry and medical-psychiatric units.