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The trapped-ion quantum charge-coupled device (QCCD) architecture is a leading candidate for advanced quantum information processing. In current QCCD implementations, imperfect ion transport and anomalous heating can excite ion motion during a calculation. To counteract this, intermediate cooling is necessary to maintain high-fidelity gate performance. Cooling the computational ions sympathetically with ions of another species, a commonly employed strategy, creates a significant runtime bottleneck. Here, we demonstrate a different approach we call exchange cooling. Unlike sympathetic cooling, exchange cooling does not require trapping two different atomic species. The protocol introduces a bank of "coolant" ions which are repeatedly laser cooled. A computational ion can then be cooled by transporting a coolant ion into its proximity. We test this concept experimentally with two 40Ca+ ions, executing the necessary transport in 107 µs, an order of magnitude faster than typical sympathetic cooling durations. We remove over 96%, and as many as 102(5) quanta, of axial motional energy from the computational ion. We verify that re-cooling the coolant ion does not decohere the computational ion. This approach validates the feasibility of a single-species QCCD processor, capable of fast quantum simulation and computation.
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Vacuum ultraviolet (VUV) light at 118 nm has been shown to be a powerful tool to ionize molecules for various gas-phase chemical studies. A convenient table top source of 118 nm light can be produced by frequency tripling 355 nm light from a Nd:YAG laser in xenon gas. This process has a low efficiency, typically producing only nJ/pulse of VUV light. Simple models of the tripling process predict that the power of 118 nm light produced should increase quadratically with increasing xenon pressure. However, experimental 118 nm production has been observed to reach a maximum and then decrease to zero with increasing xenon pressure. Here, we describe the basic theory and experimental setup for producing 118 nm light and a new proposed model for the mechanism limiting the production based on pressure broadened absorption.
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OBJECTIVES: Euthymic patients with bipolar disorder (BD) show executive impairment. Assisting cognitive function with non-pharmacological strategies has not been widely explored in BD. In schizophrenia, concomitant verbalisation (self-monitoring) during executive tests improved performance. The present pilot study assesses the effects of self-monitoring whilst completing the Wisconsin Card Sorting Test (WCST) in BD patients. METHODS: Thirty-six euthymic BD patients and 42 healthy controls participated. Twenty patients with BD and 20 controls received standard administration and 16 patients and 22 controls used self-monitoring during the test. RESULTS: ANCOVA revealed a significant "group by administration" interaction. Patients who received the standard administration were significantly worse than healthy controls (trials administered: p = .012, η p (2) = 0.17; trials to first category: p = .046, η p (2) = 0.11; failure to maintain set: p = .003, η p (2) = 0.23). BD patients who self-monitored performed significantly better than patients receiving the standard administration (trials to first category: p = .020, η p (2) = 0.17) and showed no significant differences in performance compared to controls. CONCLUSION: Self-monitoring deserves further investigation as a tool that may be helpful for patients with BD. Further exploration of the utility, generalisability, and stability of the effects of self-monitoring is needed.
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Trastorno Bipolar/psicología , Trastornos del Conocimiento/psicología , Adolescente , Adulto , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas , Proyectos Piloto , Autoimagen , Adulto JovenRESUMEN
Previous studies of facial emotion processing in bipolar disorder (BD) have reported conflicting findings. In independently conducted studies, we investigate facial emotion labeling in euthymic and depressed BD patients using tasks with static and dynamically morphed images of different emotions displayed at different intensities. Study 1 included 38 euthymic BD patients and 28 controls. Participants completed two tasks: labeling of static images of basic facial emotions (anger, disgust, fear, happy, sad) shown at different expression intensities; the Eyes Test (Baron-Cohen, Wheelwright, Hill, Raste, & Plumb, 2001), which involves recognition of complex emotions using only the eye region of the face. Study 2 included 53 depressed BD patients and 47 controls. Participants completed two tasks: labeling of "dynamic" facial expressions of the same five basic emotions; the Emotional Hexagon test (Young, Perret, Calder, Sprengelmeyer, & Ekman, 2002). There were no significant group differences on any measures of emotion perception/labeling, compared to controls. A significant group by intensity interaction was observed in both emotion labeling tasks (euthymia and depression), although this effect did not survive the addition of measures of executive function/psychomotor speed as covariates. Only 2.6-15.8% of euthymic patients and 7.8-13.7% of depressed patients scored below the 10th percentile of the controls for total emotion recognition accuracy. There was no evidence of specific deficits in facial emotion labeling in euthymic or depressed BD patients. Methodological variations-including mood state, sample size, and the cognitive demands of the tasks-may contribute significantly to the variability in findings between studies.
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Trastorno Bipolar/psicología , Expresión Facial , Adulto , Estudios de Casos y Controles , Depresión/psicología , Emociones , Función Ejecutiva , Femenino , Humanos , Masculino , Persona de Mediana Edad , Desempeño PsicomotorRESUMEN
Reduced cognitive test performance has been demonstrated in patients with bipolar disorder (BD), even when euthymic. Several studies have explored aspects of attention, including sustained attention, and reported patients show lower accuracy compared to controls. It is necessary to modify existing attentional paradigms to fully characterise such deficits. The present study sought to examine if there are changes in the profile of performance and error-types during a sustained attention task in BD. Twenty-two euthymic patients with DSM-IV diagnosed BD and 21 healthy controls were recruited. Participants completed a modified CPT-AX paradigm with a high proportion of target trials (70%) with cues and probes presented at continuous intervals. This modification increases the demands on response inhibition and permits the deconstruction of attentional/executive deficits previously described. Overall, BD patients showed significantly poorer target discriminability compared to controls. In block one (first quarter) of the task, patients showed no significant differences to controls, but by the final fourth block (last quarter) they made significantly fewer hits and more errors (both 'AX' misses and 'BX' false alarms). BD patients completed initial stages of the task similarly to controls, but as demands on the attentional system continued difficulties emerged, consistent with problems in context-maintenance.
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Atención/fisiología , Trastorno Bipolar/complicaciones , Función Ejecutiva/fisiología , Desempeño Psicomotor/fisiología , Análisis y Desempeño de Tareas , Adulto , Trastorno Bipolar/psicología , Estudios de Casos y Controles , Manual Diagnóstico y Estadístico de los Trastornos Mentales , Femenino , Humanos , Entrevistas como Asunto , Masculino , Persona de Mediana Edad , Escalas de Valoración Psiquiátrica/estadística & datos numéricos , Tiempo de Reacción/fisiologíaRESUMEN
Patients with remitted bipolar disorder (BD) have persistent cognitive deficits, but the nature and specificity of this deficit remain unclear. The authors evaluated the executive hypothesis of BD by determining whether (a) patients' executive deficits qualify as differential deficits, that is, that these significantly exceed deficits in other cognitive domains; (b) deficits in particular executive functions are evident, and (c) executive difficulties mediate declarative memory deficits in BD. The cognitive performance of 63 prospectively verified euthymic bipolar patients was compared with controls, using J. Baron and R. Trieman's (1980) method of testing for differences in nonindependent correlations. There were no differential deficits within the executive domain. Patients' generic executive performance was differentially impaired relative to primary verbal memory and retention in declarative memory, but not relative to their declarative recall, recognition, or their psychomotor performance. However, patients' executive deficit was not an artifact of their poor psychomotor performance. Executive performance accounted for all but a trivial portion of the between-group variance in declarative memory. Persistent cognitive difficulties in euthymic bipolar disorder (EBD) are thus usefully characterized as a generic dysexecutive syndrome.
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Trastorno Bipolar/epidemiología , Trastornos del Conocimiento/diagnóstico , Trastornos del Conocimiento/epidemiología , Recuperación de la Función , Manual Diagnóstico y Estadístico de los Trastornos Mentales , Femenino , Humanos , Masculino , Trastornos de la Memoria/diagnóstico , Trastornos de la Memoria/epidemiología , Persona de Mediana Edad , Pruebas Neuropsicológicas , Estudios Prospectivos , Trastornos Psicomotores/diagnóstico , Trastornos Psicomotores/epidemiología , Retención en Psicología , Índice de Severidad de la EnfermedadRESUMEN
OBJECTIVES: Converging evidence suggests that patients with remitted bipolar disorder (BD) have a persistent cognitive deficit in the executive control of working memory (WM). However, the component operations that contribute to this deficit remain unclear. The aim of the present study was to further profile the nature and specificity of WM impairment in euthymic BD. METHODS: Fifty DSM-IV-confirmed patients with euthymic BD and demographically matched controls completed a modified version of the Self-Ordered Pointing Task (SOPT) and the Cambridge Neuropsychological Test Automated Battery Pattern Recognition Test along with traditional executive and WM tasks [Stroop, initial letter Verbal Fluency (FAS), Trail-Making, Digits Forwards and Backwards]. Prospective clinical ratings over one month prior to testing confirmed that patients were euthymic at test. Absence of basal hypercortisolaemia was confirmed by serial saliva sampling. RESULTS: Error analysis revealed that whilst patients made more errors on the SOPT overall, they were no more likely to perseverate than controls. Patients' erroneous responses did not proliferate across trials, suggesting that proactive interference did not contribute to their poor performance, but serial position effects were evident where patients' errors clustered towards the end of a trial. No differences were found on the recognition memory test, in WM capacity, or on two of the three traditional executive procedures (FAS and Trail-Making). However, patients' Digits Backwards was impaired. CONCLUSIONS: These data suggest that patients with BD have a deficit in their ability to monitor the contents of WM. This deficit is not an epiphenomenon of mood, but may be due to enduring brain dysfunction, integral to bipolar illness.
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Afecto , Trastorno Bipolar/epidemiología , Trastornos de la Memoria/diagnóstico , Trastornos de la Memoria/epidemiología , Memoria a Corto Plazo , Adulto , Trastorno Bipolar/tratamiento farmacológico , Demografía , Depresión/diagnóstico , Depresión/epidemiología , Manual Diagnóstico y Estadístico de los Trastornos Mentales , Femenino , Humanos , Hidrocortisona/análisis , Masculino , Pruebas Neuropsicológicas , Estudios Prospectivos , Psicotrópicos/uso terapéutico , Reconocimiento en Psicología , Saliva/química , Encuestas y CuestionariosRESUMEN
OBJECTIVE: Neurocognitive deficits have been widely reported in patients with mood disorders. However, relatively little is known of the short-term trajectory of neurocognitive improvement once treatment has been initiated. METHOD: A neurocognitive test battery was administered to unipolar depressed (major depressive disorder, MDD) patients (aged 18-65 years) who had been medication-free for at least 6 weeks, and to healthy controls. Patients were then treated according to clinical need, predominantly with standard pharmacotherapy, and all participants were followed up within 6 months. RESULTS: Of the 25 MDD patients who returned at follow up, 11 were defined as remitted and 14 as not remitted. Significantly less baseline psychomotor dysfunction was observed in patients who remitted compared to those who did not (effect size, d =0.78, 95% confidence interval (CI) =0.07-1.44). Analysis of the change scores between assessments revealed a significantly greater improvement in verbal memory in patients who remitted compared to those who did not (d =0.73, 95%CI =0.03-1.39). CONCLUSIONS: This preliminary report suggests that there may be distinct temporal trajectories of neurocognitive improvement following remission in MDD. Aspects of neurocognitive functioning should be examined further as a means of providing a useful objective marker of treatment response.
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Encéfalo/fisiopatología , Trastornos del Conocimiento/etiología , Trastornos del Conocimiento/fisiopatología , Trastorno Depresivo Mayor/psicología , Adolescente , Adulto , Trastornos del Conocimiento/diagnóstico , Manual Diagnóstico y Estadístico de los Trastornos Mentales , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas , Aprendizaje por Asociación de Pares , Psicometría , Inducción de Remisión , Índice de Severidad de la EnfermedadRESUMEN
Visuospatial working memory theory is used to interpret the cognitive impairment in euthymic bipolar disorder. Such patients show deficits in the Corsi Blocks Test (CBT) and executive control. To understand these deficits, 20 euthymic bipolar patients and controls were administered the CBT, Visual Patterns Test (VPT), and a new visual memory task designed to make minimal demands on executive resources. Initial analyses validated the visual memory task and implicated executive involvement in the CBT and VPT. Subsequent analyses on a number of tests confirmed CBT and executive deficits while performance was normal on the VPT and visual memory test. ANCOVA indicated that impaired executive function underpinned patients' CBT performance. Implications for the interface between executive and slave systems of working memory are discussed.
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Trastorno Bipolar/psicología , Memoria a Corto Plazo , Adolescente , Adulto , Análisis de Varianza , Cognición , Trastornos del Conocimiento/psicología , Femenino , Humanos , Juicio , Masculino , Modelos Psicológicos , Pruebas Psicológicas , Percepción Espacial , Percepción VisualRESUMEN
BACKGROUND: Persistent impairments in neurocognitive function have been described in patients with bipolar disorder whose disease is in remission. However, methodological issues such as the effect of residual mood symptoms and hypercortisolaemia may confound such studies. AIMS: To assess neurocognitive functioning in prospectively verified euthymic patients with bipolar disorder. METHOD: Sixty-three patients with bipolar disorder and a matched control group completed a comprehensive neurocognitive test battery. Euthymia was confirmed in the patient group by prospective clinical ratings over 1 month prior to testing. Saliva samples were collected to profile basal cortisol secretion. RESULTS: Patients were significantly impaired across a broad range of cognitive domains. Across the domains tested, clinically significant impairment was observed in 3% to 42% of patients. Deficits were not causally associated with residual mood symptoms or hypercortisolaemia. CONCLUSIONS: Neurocognitive impairment persists in patients whose bipolar disorder is in remission. This may represent a trait abnormality and be a marker of underlying neurobiological dysfunction.
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Trastorno Bipolar/psicología , Adulto , Antidepresivos/uso terapéutico , Atención , Trastorno Bipolar/tratamiento farmacológico , Trastorno Bipolar/metabolismo , Estudios de Casos y Controles , Femenino , Humanos , Hidrocortisona/análisis , Masculino , Memoria a Corto Plazo , Persona de Mediana Edad , Análisis Multivariante , Pruebas Neuropsicológicas , Desempeño Psicomotor , Saliva/químicaRESUMEN
OBJECTIVES: Some studies have reported deficits in the perception of facial expressions among depressed individuals compared with healthy controls, while others have reported negative biases in expression perception. We examined whether altered perception of emotion reflects an underlying trait-like effect in affective disorder by examining facial expression perception in euthymic bipolar patients. METHODS: Sensitivity to six different facial expressions, as well as accuracy of emotion recognition, was examined among 17 euthymic bipolar patients and 17 healthy controls using an interactive computer program. RESULTS: No differences were found between euthymic bipolar patients and controls in terms of sensitivity to any particular emotion. Although initial analysis of the data suggested impairment in the recognition of fear among the patients, identification of this emotion was not relatively impaired compared with that of the other emotions. CONCLUSIONS: The study did not find any conclusive evidence for trait-like deficits in the perception of facially conveyed emotions in bipolar disorder. Altered perception of facial expressions that has been found to accompany depressed mood may instead reflect mood-congruent biases.