Experimental quantum speed-up in reinforcement learning agents.

As the field of artificial intelligence advances, the demand for algorithms that can learn quickly and efficiently increases. An important paradigm within artificial intelligence is reinforcement learning1, where decision-making entities called agents interact with environments and learn by updating their behaviour on the basis of the obtained feedback. The crucial question for practical applications is how fast agents learn2. Although various studies have made use of quantum mechanics to speed up the agent's decision-making process3,4, a reduction in learning time has not yet been demonstrated. Here we present a reinforcement learning experiment in which the learning process of an agent is sped up by using a quantum communication channel with the environment. We further show that combining this scenario with classical communication enables the evaluation of this improvement and allows optimal control of the learning progress. We implement this learning protocol on a compact and fully tunable integrated nanophotonic processor. The device interfaces with telecommunication-wavelength photons and features a fast active-feedback mechanism, demonstrating the agent's systematic quantum advantage in a setup that could readily be integrated within future large-scale quantum communication networks.

Management of patients with pancreatic cystic lesions: A case-based survey.

BACKGROUND: Pancreatic cystic lesions (PCL), including intraductal papillary mucinous neoplasia (IPMN), harbor different malignant potential and the optimal management is often challenging. The present study aims to depict the compliance of experts with current consensus guidelines and the accuracy of treatment recommendations stratified by the medical specialty and hospital volume. METHODS: An international survey was conducted using a set of 10 selected cases of PCL that were presented to a cohort of international experts on pancreatology. All presented cases were surgically resected between 2004 and 2015 and histopathological examination was available. Accuracy of the treatment recommendations was based on the European and international consensus guideline algorithms, and the histopathological result. RESULTS: The response rate of the survey was 26% (46 of 177 contacted experts), consisting of 70% surgeons and 30% gastroenterologists/oncologists (GI/Onc). In the case of main-duct IPMN (MD-IPMN), surgeons preferred more often the surgical approach in comparison with the GI/Onc (55 versus 44%). The mean accuracy rate based on the European and international consensus guidelines, and the histopathological result, were 71/76/38% (surgeons), and 70/73/34% (GI/Onc), respectively. High-volume centers achieved insignificantly higher accuracy scores with regard to the histopathology. Small branch-duct IPMN with cysts <2 cm and malignant potential were not identified by the guideline algorithms. CONCLUSION: The survey underlines the complexity of treatment decisions for patients with PCL; less than 40% of the recommendations were in line with the final histopathology in this selected case panel. Experts and consensus guidelines may fail to predict malignant potential in small PCL.

Prevention of component separation in complex abdominal wall surgery by Botox prehabilitation: a propensity-matched study.

AIM: To facilitate midline fascial closure in complex abdominal wall surgery, component separation techniques (CST) are usually required. However, CST is associated with an enlarged morbidity. Prehabilitation could increase the compliance of the abdominal wall and thereby decrease the necessity of myofascial release. This can be accomplished by administration of botulinum toxin type A (BTA) in the lateral abdominal wall musculature. The aim of this study was to determine the effect of BTA on the subsequent necessity to perform CST in patients with complex abdominal wall hernias. METHODS: Patients with a complex abdominal wall hernia, planned to undergo CST between July 2020 and November 2022 were included. Outcome of procedures with 300U of BTA 4 (2-6) weeks prior to surgery, were retrospectively analyzed by comparison with propensity matched subjects of an historical group. Hernia width difference was assessed by CT and operative details were included. RESULTS: A total of 13 patients with a median hernia width of 12 cm (IQR 9-14, range 24) were prehabilitated with BTA between July 2020 and November 2022. A CST was planned for all, however not required in 6/13 patients (46%) to accomplish midline fascial closure. A mean elongation of lateral abdominal wall musculature of 4.01 cm was seen in patients not requiring CST. Compared to the propensity score matched control group, a 27% reduction (p = 0.08) in the need for CST was observed. CONCLUSION: There is a tendency for decrease of necessity for CST by preoperatively administered BTA in patients with complex abdominal wall defects. Although small, as this study used propensity matched comparison, further exploration of BTA should be encouraged.

Effects of immunosuppression on alpha and beta cell renewal in transplanted mouse islets.

AIMS/HYPOTHESIS: Immunosuppressive drugs used in human islet transplantation interfere with the balance between beta cell renewal and death, and thus may contribute to progressive graft dysfunction. We analysed the influence of immunosuppressants on the proliferation of transplanted alpha and beta cells after syngeneic islet transplantation in streptozotocin-induced diabetic mice. METHODS: C57BL/6 diabetic mice were transplanted with syngeneic islets in the liver and simultaneously abdominally implanted with a mini-osmotic pump delivering BrdU alone or together with an immunosuppressant (tacrolimus, sirolimus, everolimus or mycophenolate mofetil [MMF]). Glycaemic control was assessed for 4 weeks. The area and proliferation of transplanted alpha and beta cells were subsequently quantified. RESULTS: After 4 weeks, glycaemia was significantly higher in treated mice than in controls. Insulinaemia was significantly lower in mice treated with everolimus, tacrolimus and sirolimus. MMF was the only immunosuppressant that did not significantly reduce beta cell area or proliferation, albeit its levels were in a lower range than those used in clinical settings. CONCLUSIONS/INTERPRETATION: After transplantation in diabetic mice, syngeneic beta cells have a strong capacity for self-renewal. In contrast to other immunosuppressants, MMF neither impaired beta cell proliferation nor adversely affected the fractional beta cell area. Although human beta cells are less prone to proliferate compared with rodent beta cells, the use of MMF may improve the long-term outcome of islet transplantation.

Quantum-accessible reinforcement learning beyond strictly epochal environments.

In recent years, quantum-enhanced machine learning has emerged as a particularly fruitful application of quantum algorithms, covering aspects of supervised, unsupervised and reinforcement learning. Reinforcement learning offers numerous options of how quantum theory can be applied, and is arguably the least explored, from a quantum perspective. Here, an agent explores an environment and tries to find a behavior optimizing some figure of merit. Some of the first approaches investigated settings where this exploration can be sped-up, by considering quantum analogs of classical environments, which can then be queried in superposition. If the environments have a strict periodic structure in time (i.e. are strictly episodic), such environments can be effectively converted to conventional oracles encountered in quantum information. However, in general environments, we obtain scenarios that generalize standard oracle tasks. In this work, we consider one such generalization, where the environment is not strictly episodic, which is mapped to an oracle identification setting with a changing oracle. We analyze this case and show that standard amplitude-amplification techniques can, with minor modifications, still be applied to achieve quadratic speed-ups. In addition, we prove that an algorithm based on Grover iterations is optimal for oracle identification even if the oracle changes over time in a way that the "rewarded space" is monotonically increasing. This result constitutes one of the first generalizations of quantum-accessible reinforcement learning.

[Artificial intelligence in vascular surgery and vascular medicine]. / Künstliche Intelligenz in der Gefäßchirurgie und Gefäßmedizin.

New digital technologies will also gain in importance in vascular surgery. There is a wide field of potential applications. Simulation-based training of endovascular procedures can lead to improvement in procedure-specific parameters and reduce fluoroscopy and procedural times. The use of intraoperative image-guided navigation and robotics also enables a reduction of the radiation dose. Artificial intelligence can be used for risk stratification and individualization of treatment approaches. Health apps can be used to improve the follow-up care of patients.

Charge exchange-induced X-ray emission from comet C/1999 S4 (LINEAR).

Using soft x-ray observations of the bright new comet C/1999 S4 (LINEAR) with the Chandra x-ray observatory, we have detected x-ray line emission created by charge exchange between highly ionized solar wind minor ions and neutral gases in the comet's coma. The emission morphology was symmetrically crescent shaped and extended out to 300,000 kilometers from the nucleus. The emission spectrum contains 6 lines at 320, 400, 490, 560, 600, and 670 electron volts, attributable to electron capture and radiative deexcitation by the solar wind species C(+5), C(+6), N(+7), O(+7), and O(+8). A contemporaneous 7-day soft x-ray light curve obtained using the Extreme Ultraviolet Explorer demonstrates a large increase in the comet's emission coincident with a strong solar flare on 14 and 15 July 2000.

Effect of ouabain on total vascular capacity in the dog.

Whereas the cardiac effects of digitalis glycosides have been extensively studied, less is known of the extracardiac effects of the drug, in particular the effects on vascular capacity. We investigated the effects of parenteral ouabain on vascular capacity in the dog with particular emphasis on transhepatic resistance and its interaction with splanchnic and total intravascular capacity. We studied 49 dogs on total cardiopulmonary bypass in which the splanchnic and extrasplanchnic circulations could be separately perfused and drained, and the portal vein could be vented to systemic venous pressure. The results indicate: (a) ouabain produces a net central displacement of blood at 30 min after administration of 150 +/- 70 ml (SEM), (b) this displacement occurs despite a substantial increase in transhepatic resistance, although the early rise in transhepatic resistance may delay the net displacement of blood, and (c) the decrease of overall vascular capacity is due to an effect of ouabain on the capacitance vessels of both the splanchnic and extrasplanchnic circulations. The peripheral vascular capacity effects of ouabain may therefore contribute to overall cardiac performance.

Brief screening for family psychiatric history: the family history screen.

BACKGROUND: Brief screens to collect lifetime family psychiatric history are useful in clinical practice and for identifying potential families for genetic studies. METHODS: The Family History Screen (FHS) collects information on 15 psychiatric disorders and suicidal behavior in informants and their first-degree relatives. Since each question is posed only once about all family members as a group, the administrative time is 5 to 20 minutes, depending on family size and illness. Data on the validity against best-estimate (BE) diagnosis based on independent and blind direct interviews on 289 probands and 305 relatives and test-retest reliability across 15 months in 417 subjects are presented. RESULTS: Agreement between FHS and BE diagnosis for proband and relative self-report had median sensitivity (SEN) of 67.6 and 71.1 respectively; median specificity (SPC) was 87.6 and 89.4, respectively. Marked decrease in SEN occurred when a single informant (the proband) reported on a relative (median, 37.5); however, median SPC was 95.8. Use of more than 1 informant substantially improved SEN (median, 68.2), with a modest reduction in SPC (median, 86.8). Test-retest reliability across 15 months resulted in a median kappa of 0.56. CONCLUSIONS: The FHS is a promising brief screen for collecting lifetime psychiatric history on an informant and/or first-degree relatives. Its validity is best demonstrated for major depression, anxiety disorders, substance dependence (alcohol and drug dependence), and suicide attempts. It is not a substitute for more lengthy family history if more detail on diagnosis is required.

Is the comorbidity between social phobia and panic disorder due to familial cotransmission or other factors?

BACKGROUND: We previously reported significantly elevated rates of social phobia in relatives of probands with panic disorder compared with relatives of other proband groups. This study further investigates the relationship between social phobia and panic disorder. METHOD: This sample is from a family study that included 193 probands from four mutually exclusive groups (patients with panic disorder, patients with panic disorder and major depression, patients with early-onset major depression, and normal controls) and 1047 of their adult first-degree relatives. Best-estimate diagnoses were completed using DSM-III-R criteria. RESULTS: Social phobia and agoraphobia aggregate in the families of probands with panic disorder without major depression. Social phobia frequently co-occurs with panic disorder in relatives, but the risk for comorbidity does not vary across proband groups. CONCLUSIONS: The familial aggregation of social phobia with panic disorder may be explained by the aggregation of panic disorder in relatives of probands with panic disorder combined with the tendency for panic disorder to occur comorbidly with social phobia in individuals.

Children with prepubertal-onset major depressive disorder and anxiety grown up.

BACKGROUND: The continuity in adulthood of major depressive disorder (MDD) first arising before puberty is largely unknown. This information could guide early treatment and clarify the appropriateness of including children with MDD in genetic studies. METHODS: Eighty-three subjects with onset of MDD, 44 subjects with anxiety disorder and no MDD, and 91 subjects with no evidence of past or current psychiatric disorders were assessed by two psychiatrists before puberty (Tanner stage < III) and were evaluated 10 to 15 years later as adults by an independent team without knowledge of the initial diagnosis. RESULTS: The clinical outcome of children with prepubertal-onset MDD in adulthood includes a high risk of suicide attempts (nearly 3-fold compared with normal controls and 2-fold compared with children with anxiety) and bipolar disorder. Compared with controls, both the children with MDD and those with anxiety went on to have increased risk of substance abuse and conduct disorder but not other disorders, increased use of longterm psychiatric and medical services, and overall impaired functioning. Children with prepubertal-onset MDD with a recurrence of MDD during follow-up had higher rates of MDD in their first-degree relatives. CONCLUSIONS: There is high morbidity in clinically referred children with prepubertal-onset MDD and anxiety, but continuity and specificity of MDD or anxiety disorder in adulthood is less clear. Caution is warranted in selecting clinically referred children with prepubertal-onset MDD for inclusion in genetic studies unless they have a family history of MDD and recurrence of MDD over time.

Premorbid polysomnographic signs in depressed adolescents: a reanalysis of EEG sleep after longitudinal follow-up in adulthood.

BACKGROUND: This is a report of a clinical follow-up study (10-15 years later as young adults) of adolescent major depressives and normal control subjects. Polysomnographic data were obtained during the original study period when the subjects were adolescent (time 1). With clinical follow-up (time 2) assessments in hand, our objective was to ascertain whether there were any premorbid polysomnographic signs associated with depression during adolescence. METHODS: Based upon initial (during adolescence) and follow-up clinical assessments (as adults), new subject groupings were generated: depression-free normal subjects and original normal subjects who experienced a depressive episode during the follow-up period (latent depressives). Suicidality and recurrence of depression were also examined. Multivariate analysis of covariance was used to analyze group differences in sleep measures and logistic regression for predicting three outcomes: lifetime depression, lifetime suicidality, and recurrence. RESULTS: Comparison of the depression-free normal subjects, the latent depressives, and the original major depressives revealed significant differences for sleep latency and sleep period time. Comparing all lifetime depressives (original major depressives and the latent depressives) to depression-free normal subjects revealed significantly more stages 3 and 4 combined (ST34) sleep and greater sleep period times among the depressives. An analysis involving the presence or absence of suicidality revealed no overall significant differences between the groups. Comparison of the lifetime depressives grouped by nonrecurrent and recurrent depressive course to the depression-free normal subjects revealed significant difference for sleep period time. Using logistic regression, we found that a longer sleep latency and sleep period time significantly predicted lifetime depression. Gender, ST34 sleep, and an interaction term for ST34 sleep and REM latency significantly predicted lifetime suicidality. CONCLUSIONS: There was evidence of premorbid sleep abnormalities during adolescence. A general pattern of sleep disruption around sleep onset and during the first 100 min of the sleep period and overall sleep was evident among the major and lifetime depressives, involving sleep latency (initial insomnia), sleep period time (hypersomnia), REM latency, and slow-wave sleep. This adds to the body of literature that highlights the importance of the first 100 min of the sleep period in depression.

Nocturnal growth hormone secretion studies in adolescents with or without major depression re-examined: integration of adult clinical follow-up data.

BACKGROUND: Early sleep is associated with an increased secretion of human growth hormone (GH) through muscarinic inhibition of somatostatin, a GH suppressant. A clinical follow-up was performed approximately 1 decade after depressed and psychiatrically "normal" control adolescents, who were now young adults, had undergone baseline serial GH measurements over a 24-hour period on the third night of sleep polysomnography studies. METHODS: The study population consisted of 77 young adults who had received a diagnosis of adolescent major depressive disorder and had participated in the adolescent sleep and neuroendocrine studies. Alternatively, the young adult subjects were assessed as normal adolescent control subjects free of any psychiatric diagnosis. Blood samples had been collected for GH every 20 min during the 24-hour period coinciding with the third consecutive night of sleep electroencephalography. Subjects, now in young adulthood, were relocated and blindly reinterviewed using the Schedule for Affective Disorders and Schizophrenia (lifetime version). The original adolescent nocturnal GH data were analyzed in light of the information obtained regarding clinical course into adulthood. RESULTS: A substantial proportion of the nominally normal control group developed at least one episode of major depression or dysthymia during the follow-up period. "Latent" depressive subjects differed from depression-free control subjects by having exhibited a significantly more rapid increase of adolescent nocturnal GH secretion following sleep onset. Of the subjects who had experienced at least one lifetime major depressive episode during the follow-up, the subgroup who would go on to make suicide attempts secreted significantly greater amounts of GH during the first 4 hours of sleep. Adults with lifetime depression exhibited significantly reduced levels of GH in the 100 min preceding sleep onset during adolescence. CONCLUSIONS: Assignment of subjects based on longitudinal clinical follow-up into adulthood revealed that the sleep-related GH secretion paradigm has predictive value for future depressive episodes and future suicide attempts. Dysfunction of complex sleep-onset mechanisms may be a premorbid marker of depression and suicidal behavior.

Clozapine treatment of psychosis in Parkinson's disease: a report of five consecutive cases.

BACKGROUND: Clozapine has gained acceptance as an antipsychotic in treatment-resistant schizophrenia. Its low propensity to induce extrapyramidal side effects makes clozapine an attractive treatment for patients with Parkinson's disease and dopaminomimetic psychosis. Recent evidence demonstrates that Parkinson's patients are exquisitely sensitive to both the antipsychotic and the potential extrapyramidal effects of clozapine. The uncontrolled studies suggest that low-dose clozapine may be efficacious in this population. The dose range, side effect profiles, and length of treatment varied in these reports. METHOD: We report our experience with five patients with Parkinson's disease and psychosis who were treated with clozapine in an open trial. RESULTS: Three patients were successfully treated with clozapine (25-100 mg/day, mean = 66.7 mg) without worsening their parkinsonism. Adverse effects unrelated to the motor disability required discontinuation of clozapine in the other two patients. At 1- to 2-year follow-up, each patient had required increased dosages of clozapine (75-150 mg/day, mean = 125 mg) for continued management of their psychosis and parkinsonism. The higher dose range was well tolerated. CONCLUSION: These results suggest that clozapine may effectively treat psychosis in Parkinson's disease.

Noninvasive evaluation of hand circulation before radial artery harvest for coronary artery bypass grafting.

OBJECTIVE: Radial artery harvesting for coronary artery bypass may lead to digit ischemia if collateral hand circulation is inadequate. The modified Allen's test is the most common preoperative screening test used. Unfortunately, this test has high false-positive and false-negative rates. The purpose of this study was to compare the results of a modified Allen's test with digit pressure change during radial artery compression for assessing collateral circulation before radial artery harvest. METHODS: One hundred twenty-nine consecutive patients were studied before coronary artery bypass operations. A modified Allen's test was performed with Doppler ultrasound to assess blood flow in the superficial palmar arch before and during radial artery compression. A decreased audible Doppler signal after radial artery compression was considered a positive modified Allen's test. First and second digit pressures were measured before and during radial artery compression. A decrease in digit pressure of 40 mm Hg or more (digit DeltaP) with radial artery compression was considered positive. RESULTS: Seven of 14 dominant extremities (50%) and 8 of the 16 nondominant extremities (50%) with a positive modified Allen's test had a digit DeltaP of less than 40 mm Hg (false positive). Sixteen of 115 dominant extremities (14%) and 5 of 112 nondominant extremities (4%) with a negative Allen's test had a digit DeltaP of 40 mm Hg or more with radial artery compression (false negative). CONCLUSION: Use of the modified Allen's test for screening before radial artery harvest may unnecessarily exclude some patients from use of this conduit and may also place a number of patients at risk for digit ischemia from such harvest. Direct digit pressure measurement is a simple, objective method that may more precisely select patients for radial artery harvest. Additional studies are needed to define objective digital pressure criteria that will accurately predict patients at risk for hand ischemia after radial harvest.

Effects of desipramine on autonomic input to the heart.

OBJECTIVE: To examine the impact of age on the effects of desipramine (DMI) on autonomic input to the heart. METHOD: Twenty-four-hour electrocardiograms were obtained from 42 subjects, aged 7 to 66 years, while off and on DMI. To obtain measures of autonomic input to the heart, heart rate variability was assessed via spectral analysis of RR interval variability. RESULTS: DMI treatment was associated with a significant increase in 24-hour mean heart rate and significant decreases in RR interval variability in all spectral bands, including in the high-frequency band, which provides a measure of parasympathetic input to the heart. RR interval variability was greater in younger individuals both off and on DMI. CONCLUSIONS: DMI treatment was associated with a marked decline in RR interval variability, indicating that DMI affects autonomic input to the heart. Specifically, DMI reduced parasympathetic input, which, in theory, may increase vulnerability to arrhythmias. However, the magnitude of DMI's impact on RR interval variability did not vary with age.

Computer simulation of intracranial pressure changes during induction of anesthesia: comparison of thiopental, propofol, and etomidate.

We have developed a computer model of cerebrovascular hemodynamics that interacts with a pharmacokinetic drug model. We used this model to examine the effects of various stimuli occurring during anesthesia on cerebral blood flow (CBF) and intracranial pressure (ICP). The model is a seven-compartment constant-volume system. A series of resistances and compliances relate blood and cerebrovascular fluid fluxes to pressure gradients between compartments. Variable arterial-arteriolar resistance (Ra-ar) and arteriolar-capillary resistance (Rar-c) simulate autoregulation and drug effects, respectively. Rar-c is also used to account for the effect of CO2 on the cerebral circulation. A three-compartment pharmacokinetic model predicts concentration-time profiles of intravenous induction agents. The effect-site compartment is included to account for disequilibrium between drug plasma and biophase concentrations. The simulation program is written in VisSim dynamic simulation language for an IBM-compatible personal computer. Using the model, we have predicted ICP responses during induction of anesthesia for a simulated patient with normal as well as elevated ICP. Simulation shows that the induction dose of intravenous anesthetic reduces ICP up to 30% (propofol > thiopental > etomidate). The duration of this effect is limited to less than 5 minutes by rapid drug redistribution and cerebral autoregulation. Subsequent laryngoscopy causes acute intracranial hypertension, exceeding the initial ICP. ICP elevation is more pronounced in a nonautoregulated cerebral circulation. Simulation results are in good agreement with the available experimental data. The presented model allows comparison of various drug administration schedules to control ICP.

Upper extremity venous gangrene following coronary artery bypass. A case report and review of the literature.

Acute symptomatic upper extremity deep vein thrombosis (DVT) are estimated to account for only 2-4% of all deep vein thrombosis. Upper extremity DVT leading to phlegmasia cerulea dolens (PCD) occurs in an estimated 2-5% of these cases. Progression of PCD to venous gangrene is extremely rare with only 16 previously reported cases in the literature. Only 7 of the cited cases document significant tissue loss. This report describes a 61-year-old male who developed upper extremity DVT complicated by PCD which led to venous gangrene and limb loss.

Factors affecting parents' perceptions of temperament in early infancy.

Parents' perceptions of temperament in their three-month-old infants were examined in relation to prenatally measured parental characteristics and to objective indices of infant behavior at three months. Infant behavior and parental characteristics appear to make independent contributions to parents' perceptions in early infancy.

The relative effects of three expressive methods upon the speech intelligibility of profoundly deaf speakers.

Two studies, conducted over a nine month interval, were designed to evaluate the relative effects of three expressive methods (speech alone, speech and signs, and speech with cues) upon speech intelligibility. Five profoundly deaf adults, who were receiving continuous speech training, were recorded reading lists of individual words under all three expressive modes. Listeners were required to identify through a multiple choice format the target stimuli from auditory presentations only. Study I results indicated that speech with cues produced the highest level of intelligibility, while speech and signs produced the lowest level. Study II, with an expanded set of word stimuli, found that speech alone produced a 65% rate of correct identification by listeners; speech and signs again produced the lowest rate of correct identifications. Implications for the assessment and understanding of speech intelligibility are considered.