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1.
J Nutr Health Aging ; 27(12): 1281-1283, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38151880
2.
J Neurosci ; 43(25): 4738-4749, 2023 06 21.
Artículo en Inglés | MEDLINE | ID: mdl-37230765

RESUMEN

The impact of tau pathology on sleep microarchitecture features, including slow oscillations, spindles, and their coupling, has been understudied, despite the proposed importance of these electrophysiological features toward learning and memory. Dual orexin receptor antagonists (DORAs) are known to promote sleep, but whether and how they affect sleep microarchitecture in the setting of tauopathy is unknown. In the PS19 mouse model of tauopathy MAPT (microtubule-associated protein tau) P301S (both male and female), young PS19 mice 2-3 months old show a sleep electrophysiology signature with markedly reduced spindle duration and power and elevated slow oscillation (SO) density compared with littermate controls, although there is no significant tau hyperphosphorylation, tangle formation, or neurodegeneration at this age. With aging, there is evidence for sleep disruption in PS19 mice, characterized by reduced REM duration, increased non-REM and REM fragmentation, and more frequent brief arousals at the macrolevel and reduced spindle density, SO density, and spindle-SO coupling at the microlevel. In ∼33% of aged PS19 mice, we unexpectedly observed abnormal goal-directed behaviors in REM, including mastication, paw grasp, and forelimb/hindlimb extension, seemingly consistent with REM behavior disorder (RBD). Oral administration of DORA-12 in aged PS19 mice increased non-REM and REM duration, albeit with shorter bout lengths, and increased spindle density, spindle duration, and SO density without change to spindle-SO coupling, power in either the SO or spindle bands, or the arousal index. We observed a significant effect of DORA-12 on objective measures of RBD, thereby encouraging future exploration of DORA effects on sleep-mediated cognition and RBD treatment.SIGNIFICANCE STATEMENT The specific effect of tauopathy on sleep macroarchitecture and microarchitecture throughout aging remains unknown. Our key findings include the following: (1) the identification of a sleep EEG signature constituting an early biomarker of impending tauopathy; (2) sleep physiology deteriorates with aging that are also markers of off-line cognitive processing; (3) the novel observation that dream enactment behaviors reminiscent of RBD occur, likely the first such observation in a tauopathy model; and (4) a dual orexin receptor antagonist is capable of restoring several of the sleep macroarchitecture and microarchitecture abnormalities.


Asunto(s)
Trastorno de la Conducta del Sueño REM , Tauopatías , Masculino , Femenino , Ratones , Animales , Antagonistas de los Receptores de Orexina/farmacología , Sueño/fisiología , Tauopatías/tratamiento farmacológico , Fenotipo
3.
Am J Med Genet A ; 191(7): 1968-1972, 2023 07.
Artículo en Inglés | MEDLINE | ID: mdl-37092751

RESUMEN

Variants in the RNA binding protein (RBP) U2AF2 are hypothesized to cause a novel neurodevelopmental disorder. Here, we report a patient with a de novo missense variant in U2AF2, the second case report of the same variant, and third case report overall. The patient in this report has a history of global developmental delay, dysmorphic features, and epilepsy. This presentation is consistent with the previous case report with the same U2AF2 variant and with a recent case report of another U2AF2 variant, strengthening the evidence that variants in U2AF2 are the cause of a novel neurodevelopmental disorder.


Asunto(s)
Epilepsia , Discapacidad Intelectual , Anomalías Musculoesqueléticas , Trastornos del Neurodesarrollo , Niño , Humanos , Discapacidades del Desarrollo/genética , Trastornos del Neurodesarrollo/genética , Mutación Missense/genética , Epilepsia/diagnóstico , Epilepsia/genética , Discapacidad Intelectual/genética , Factor de Empalme U2AF/genética
4.
Phys Chem Chem Phys ; 25(8): 6225-6231, 2023 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-36756814

RESUMEN

The stochastic wave function method is proposed to study the diffusion regimes of alkali atoms on metallic surfaces. The Lindblad approach, based on the microscopic Hamiltonian information in the Caldeira-Leggett model, is presented and numerical calculations of the dynamics are carried out to characterize surface diffusion for two different systems: Na-Cu(111) and Li-Cu(111). Calculations of the intermediate scattering function for an isolated adsorbate are compared, in the Brownian limit, with results deduced from helium spin-echo (HeSE) experiments after reducing them to single adsorbate dynamics. To illustrate the method we present the dependence on momentum transfer and the temperature dependency. Results show that the experiment can be described at a quantitative level by the 1-D quantum model (reduced dimensionality).

5.
Sci Rep ; 13(1): 1060, 2023 01 19.
Artículo en Inglés | MEDLINE | ID: mdl-36658180

RESUMEN

Mutations at specific hotspots in non-coding regions of ADGRG6, PLEKHS1, WDR74, TBC1D12 and LEPROTL1 frequently occur in bladder cancer (BC). These mutations could function as biomarkers for the non-invasive detection of BC but this remains largely unexplored. Massively-parallel sequencing of non-coding hotspots was applied to 884 urine cell pellet DNAs: 591 from haematuria clinic patients (165 BCs, 426 non-BCs) and 293 from non-muscle invasive BC surveillance patients (29 with recurrence). Urine samples from 142 non-BC haematuria clinic patients were used to optimise variant calling. Non-coding mutations are readily detectable in the urine of BC patients and undetectable, or present at much lower frequencies, in the absence of BC. The mutations can be used to detect incident BC with 66% sensitivity (95% CI 58-75) at 92% specificity (95% CI 88-95) and recurrent disease with 55% sensitivity (95% CI 36-74) at 85% specificity (95% CI 80-89%) using a 2% variant allele frequency threshold. In the NMIBC surveillance setting, the detection of non-coding mutations in urine in the absence of clinically detectable disease was associated with an increased relative risk of future recurrence (RR = 4.62 (95% CI 3.75-5.48)). As urinary biomarkers, non-coding hotspot mutations behave similarly to driver mutations in BC-associated genes and could be included in biomarker panels for BC detection.


Asunto(s)
Hematuria , Neoplasias de la Vejiga Urinaria , Humanos , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/orina , Neoplasias de la Vejiga Urinaria/diagnóstico , Neoplasias de la Vejiga Urinaria/genética , Neoplasias de la Vejiga Urinaria/orina , Vejiga Urinaria , Mutación , Proteínas de Unión al ARN/genética
6.
Phys Chem Chem Phys ; 24(43): 26539-26546, 2022 Nov 09.
Artículo en Inglés | MEDLINE | ID: mdl-36305197

RESUMEN

In understanding the nature of contrast in the emerging field of neutral helium microscopy, it is important to identify if there is an atom-surface scattering distribution that can be expected to apply broadly across a range of sample surfaces. Here we present results acquired in a scanning helium microscope (SHeM) under typical operating conditions, from a range of surfaces in their native state, i.e. without any specialist sample preparation. We observe diffuse scattering, with an approximately cosine distribution centred about the surface normal. The 'cosine-like' distribution is markedly different from those distributions observed from the well-prepared, atomically pristine, surfaces typically studied in helium atom scattering experiments. Knowledge of the typical scattering distribution in SHeM experiments provides a starting basis for interpretation of topographic contrast in images, as well as a reference against which more exotic contrast mechanisms can be compared.

7.
Rev Sci Instrum ; 92(7): 073305, 2021 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-34340407

RESUMEN

The design of a high-efficiency mass spectrometer is described, aimed at residual gas detection of low mass species using low-energy electron impact, with particular applications in helium atom microscopy and atomic or molecular scattering. The instrument consists of an extended ionization volume, where electrons emitted from a hot filament are confined using a solenoidal magnetic field to give a high ionization probability. Electron space charge is used to confine and extract the gas ions formed, which are then passed through a magnetic sector mass filter before reaching an ion counter. The design and implementation of each of the major components are described in turn, followed by the overall performance of the detector in terms of mass separation, detection efficiency, time response, and background count rates. The linearity of response with emission current and magnetic field is discussed. The detection efficiency for helium is very high, reaching as much as 0.5%, with a time constant of (198 ± 6) ms and a background signal equivalent to an incoming helium flux of (8.7 ± 0.2) × 106 s-1.

8.
Neonatology ; 118(4): 500-504, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34004602

RESUMEN

We report a case of a male neonate delivered urgently via cesarean at thirty-five 5/7 weeks gestation for non-reassuring fetal monitoring who was found to have severe anemia at birth that could not be explained by acute blood loss. He was born to a 24-year-old mother, whose pregnancy was complicated by abnormal ultrasound findings, including a radial ray defect and fetal growth restriction. Trio rapid whole-exome sequencing (rWES) confirmed Diamond-Blackfan anemia in both the neonate and mother. This case highlights the importance of fetal surveillance and the clinical utility of rWES in the neonatal intensive care setting.


Asunto(s)
Anemia de Diamond-Blackfan , Anemia de Diamond-Blackfan/genética , Femenino , Humanos , Recién Nacido , Masculino , Embarazo , Secuenciación del Exoma , Adulto Joven
9.
Orphanet J Rare Dis ; 16(1): 136, 2021 03 18.
Artículo en Inglés | MEDLINE | ID: mdl-33736665

RESUMEN

BACKGROUND: An identical homozygous missense variant in EIF3F, identified through a large-scale genome-wide sequencing approach, was reported as causative in nine individuals with a neurodevelopmental disorder, characterized by variable intellectual disability, epilepsy, behavioral problems and sensorineural hearing-loss. To refine the phenotypic and molecular spectrum of EIF3F-related neurodevelopmental disorder, we examined independent patients. RESULTS: 21 patients were homozygous and one compound heterozygous for c.694T>G/p.(Phe232Val) in EIF3F. Haplotype analyses in 15 families suggested that c.694T>G/p.(Phe232Val) was a founder variant. All affected individuals had developmental delays including delayed speech development. About half of the affected individuals had behavioral problems, altered muscular tone, hearing loss, and short stature. Moreover, this study suggests that microcephaly, reduced sensitivity to pain, cleft lip/palate, gastrointestinal symptoms and ophthalmological symptoms are part of the phenotypic spectrum. Minor dysmorphic features were observed, although neither the individuals' facial nor general appearance were obviously distinctive. Symptoms in the compound heterozygous individual with an additional truncating variant were at the severe end of the spectrum in regard to motor milestones, speech delay, organic problems and pre- and postnatal growth of body and head, suggesting some genotype-phenotype correlation. CONCLUSIONS: Our study refines the phenotypic and expands the molecular spectrum of EIF3F-related syndromic neurodevelopmental disorder.


Asunto(s)
Labio Leporino , Fisura del Paladar , Discapacidad Intelectual , Microcefalia , Trastornos del Neurodesarrollo , Factor 3 de Iniciación Eucariótica , Humanos , Discapacidad Intelectual/genética , Trastornos del Neurodesarrollo/genética
10.
Ann R Coll Surg Engl ; 103(3): 160-166, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33645278

RESUMEN

INTRODUCTION: The COVID-19 pandemic resulted in reconfiguration of the NHS. Elective services were stopped and trauma services focused on decreasing patient-clinician interactions and managing injuries nonoperatively wherever possible. The everyday life of the general public changed dramatically with the introduction of a national lockdown to prevent the spread of COVID-19. This paper looks at the experience of a South West London trauma unit. MATERIALS AND METHODS: All patients reviewed in fracture clinic and by the orthopaedic on-call team between 23 March to 23 April 2020 were included. Data on the mechanism of injury and whether this was a usual activity, the injury sustained and its management were collected. RESULTS: A total of 167 trauma injuries were seen, compared with 735 new patients with injuries in the previous month. The number of trauma operations completed decreased by 38%; 55% of injuries occurred inside the home and 44% outside the home during daily exercise. Some 31% of injuries were secondary to a new activity taken up during lockdown. Three open fractures and two polytrauma cases were seen that would have normally been managed at the local major trauma centre. CONCLUSION: Overall, both the number of injuries seen and trauma operations completed during the enforced lockdown decreased. This is probably due to a change in the way the general public are living their lives, and the reconfigurations within the NHS in response to the COVID-19 pandemic. This is an interesting time within trauma and orthopaedic departments, as they continue to adapt to the changing injuries and working environment.


Asunto(s)
Accidentes Domésticos/estadística & datos numéricos , Ejercicio Físico , Fracturas Óseas/epidemiología , Centros Traumatológicos , Accidentes por Caídas/estadística & datos numéricos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Ciclismo/lesiones , COVID-19/prevención & control , Niño , Preescolar , Control de Enfermedades Transmisibles , Femenino , Fracturas del Cuello Femoral/epidemiología , Fracturas del Cuello Femoral/etiología , Fracturas del Cuello Femoral/cirugía , Fijación Interna de Fracturas , Fracturas Óseas/etiología , Fracturas Óseas/cirugía , Jardinería , Humanos , Lactante , Londres/epidemiología , Masculino , Persona de Mediana Edad , Fracturas del Radio/epidemiología , Fracturas del Radio/etiología , Fracturas del Radio/cirugía , SARS-CoV-2 , Adulto Joven
11.
Clin Radiol ; 76(2): 160.e1-160.e14, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33019967

RESUMEN

AIM: To report the magnetic resonance imaging (MRI) findings from a retrospective case analysis of children with septo-optic dysplasia (SOD), a rare congenital disorder characterised by any combination of midline brain defects, optic nerve hypoplasia (ONH), and hypothalamic-pituitary dysfunction. MATERIALS AND METHODS: SOD was defined radiologically as complete or partial septum pellucidum (SP) absence with hypoplasia of at least one of the optic nerves and/or chiasm. Local MRI databases were searched for SOD cases in children over an 18-year period, and studies reviewed by two consultant paediatric neuroradiologists. The extent of structural SP, optic nerve, chiasm, and hypothalamic-pituitary involvement was recorded, along with coexisting brain abnormalities. RESULTS: Forty-eight cases of SOD were found; 44/48 (92%) demonstrated complete SP absence whereas 4/48 (8%) had partial absence. Eight of 48 cases (17%) exhibited unilateral ONH. Fifty-one percent of cases, where the pituitary was identified on MRI, demonstrated a structural pituitary abnormality, which included an ectopic posterior bright spot in 6%. The olfactory nerves were hypoplastic in 5/48 cases (10%). Twenty-seven of the 48 cases (56%) had another brain abnormality, resulting from some form of cortical formation abnormality/schizencephaly in 21/48 (44%). CONCLUSION: A high rate of associated brain abnormalities was found in the present cohort, including structural pituitary abnormalities in 51% and cortical formation abnormalities/schizencephaly in 44%. This suggests there is not a single cause for SOD, rather SOD is the phenotypic end point from multiple aetiological events. Individual children with SOD may have coexisting intracranial abnormalities, and, hence, high-quality MRI is required in all.


Asunto(s)
Encéfalo/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Displasia Septo-Óptica/diagnóstico por imagen , Adolescente , Niño , Preescolar , Estudios de Cohortes , Inglaterra , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Estudios Retrospectivos
12.
HIV Med ; 21(9): 588-598, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-32776431

RESUMEN

OBJECTIVES: We report the frequency of previous HIV testing at baseline in men who have sex with men (MSM) who enrolled in an HIV self-testing (HIVST) randomized controlled trial [an HIV self-testing public health intervention (SELPHI)]. METHODS: Criteria for enrolment were age ≥ 16 years, being a man (including trans men) who ever had anal intercourse (AI) with a man, not being known to be HIV positive and having consented to national HIV database linkage. Using online survey baseline data (2017-2018), we assessed associations with never having tested for HIV and not testing in the previous 6 months, among men who reported at least two recent condomless AI (CAI) partners. RESULTS: A total of 10 111 men were randomized; the median age was 33 years [interquartile range (IQR) 26-44 years], 89% were white, 20% were born outside the UK, 0.8% were trans men, 47% were degree educated, and 8% and 4% had ever used and were currently using pre-exposure prophylaxis (PrEP), respectively. In the previous 3 months, 89% reported AI and 72% reported CAI with at least one male partner. Overall, 17%, 33%, 54%, and 72% had tested for HIV in the last 3 months, 6 months, 12 months and 2 years, respectively; 13% had tested more than 2 years ago and 15% had never tested. Among 3972 men reporting at least two recent CAI partners, only 22% had tested in the previous 3 months. Region of residence and education level were independently associated with recent HIV testing. Among current PrEP users, 15% had not tested in the previous 6 months. CONCLUSIONS: Most men in SELPHI, particularly those reporting at least two CAI partners and current PrEP users, were not testing in line with current UK recommendations. The results of the trial will inform whether online promotion of HIVST addresses ongoing testing barriers.


Asunto(s)
Infecciones por VIH/diagnóstico , Prueba de VIH/métodos , Homosexualidad Masculina/estadística & datos numéricos , Profilaxis Pre-Exposición/estadística & datos numéricos , Conducta Sexual/clasificación , Adulto , Infecciones por VIH/epidemiología , Infecciones por VIH/prevención & control , Humanos , Masculino , Salud Pública , Autoevaluación , Conducta Sexual/estadística & datos numéricos , Parejas Sexuales , Reino Unido/epidemiología , Sexo Inseguro/estadística & datos numéricos
13.
Public Health ; 182: 193-198, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32375100

RESUMEN

OBJECTIVE: Few parent-targeted interventions have examined the mechanisms of action by which the intervention changes child behavior. The purpose of this study was to test the theoretical and behavioral mediators of the Smart Moms intervention on changes in child sugar-sweetened beverage and juice (SSB/juice) consumption. STUDY DESIGN: This is a secondary mediation analysis of data from a 6-month randomized controlled trial (N = 51 mother-child dyads) of a mobile phone-based program to reduce child SSB/juice intake compared with a waitlist control group. METHODS: Linear mixed models compared changes in intervention targets from baseline to 3 months between treatment groups. Intervention targets that changed significantly between groups were tested in a multiple mediation model to evaluate their significance as mediators of change in child SSB/juice at 6 months. RESULTS: Maternal beverage consumption but no other behavioral or theoretical intervention targets mediated the effect of the intervention on the reduction in child SSB/juice at 6 months. There were few mediators of the intervention on child SSB/juice change. CONCLUSION: Greater longitudinal research is needed to understand predictors of child dietary changes to inform future intervention efforts. In addition, a greater focus on the measurement of theoretical constructs in family-based child obesity prevention research is needed.


Asunto(s)
Conducta Alimentaria , Promoción de la Salud/métodos , Madres , Obesidad Infantil/prevención & control , Bebidas Azucaradas , Adulto , Terapia Conductista/métodos , Teléfono Celular , Preescolar , Dieta , Femenino , Jugos de Frutas y Vegetales , Humanos , Masculino , Padres , Edulcorantes/administración & dosificación
14.
Sci Rep ; 10(1): 2053, 2020 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-32029779

RESUMEN

Scanning helium microscopy is an emerging form of microscopy using thermal energy neutral helium atoms as the probe particle. The very low energy combined with lack of charge gives the technique great potential for studying delicate systems, and the possibility of several new forms of contrast. To date, neutral helium images have been dominated by topographic contrast, relating to the height and angle of the surface. Here we present data showing contrast resulting from specular reflection and diffraction of helium atoms from an atomic lattice of lithium fluoride. The signature for diffraction is evident by varying the scattering angle and observing sharp features in the scattered distribution. The data indicates the viability of the approach for imaging with diffraction contrast and suggests application to a wide variety of other locally crystalline materials.

15.
J Prev Alzheimers Dis ; 7(1): 37-42, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32010924

RESUMEN

In 358 participants of the Tasmanian Healthy Brain Project, we quantified the cognitive consequences of engaging in varying loads of university-level education in later life, and investigated whether or not BDNF Val66Met affected outcomes. Assessment of neuropsychological, health, and psychosocial function was undertaken at baseline, 12-month, and 24-month follow-up. Education load was positively associated with change in language processing performance, but this effect did not reach statistical significance (P = 0.064). The BDNF Val66Met polymorphism significantly moderated the extent to which education load was associated with improved language processing (P = 0.026), with education load having a significant positive relationship with cognitive change in BDNF Met carriers but not in BDNF Val homozygotes. In older adults who carry BDNF Met, engaging in university-level education improves language processing performance in a load-dependent manner.


Asunto(s)
Envejecimiento/genética , Factor Neurotrófico Derivado del Encéfalo/genética , Cognición , Polimorfismo Genético/genética , Rendimiento Académico , Anciano , Envejecimiento/fisiología , Estudios de Casos y Controles , Disfunción Cognitiva/prevención & control , Humanos , Persona de Mediana Edad , Pruebas Neuropsicológicas , Tasmania , Universidades
16.
Sleep ; 43(3)2020 03 12.
Artículo en Inglés | MEDLINE | ID: mdl-31608388

RESUMEN

Offline gains in motor performance after initial motor learning likely depend on sleep, but the molecular mechanisms by which this occurs are understudied. Regulation of mRNA translation via p70 S6 kinase 1 (S6K1) signaling represents one potential mechanism, as protein synthesis is thought to be increased during sleep compared to wake and is necessary for several forms of long-term memory. Using phosphorylation of ribosomal protein S6 (RpS6) as a readout of S6K1 activity, we demonstrate that a period of 10 h of acute sleep disruption impairs both S6K1 signaling and offline gains in motor performance on the rotarod in adult wild type C57/Bl6 mice. Rotarod motor learning results in increased abundance of RpS6 in the striatum, and inhibition of S6K1 either indirectly with rapamycin or directly with PF-4708671 diminished the offline improvement in motor performance without affecting the initial acquisition of rotarod motor learning when sleep is normal. In sum, S6K1 activity is required for sleep-dependent offline gains in motor performance and is inhibited following acute sleep disruption, while motor learning increases the abundance of striatal RpS6. Thus, S6K1 signaling represents a plausible mechanism mediating the beneficial effects of sleep on motor performance.


Asunto(s)
Proteínas Quinasas S6 Ribosómicas 70-kDa , Transducción de Señal , Animales , Ratones , Fosforilación , Proteínas Quinasas S6 Ribosómicas 70-kDa/metabolismo , Sirolimus , Sueño
17.
HIV Med ; 21(3): 189-197, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-31821698

RESUMEN

OBJECTIVES: SELPHI (HIV Self-Testing Public Health Intervention) is the largest randomized controlled trial (RCT) of HIV self-testing (HIVST) in a high-income setting to date, and has recruited 10 000 men who have sex with men (cis- and transgender) and transgender women who have sex with men. This qualitative substudy aimed to explore how those utilizing self-tests experience HIVST and the implications for further intervention development and scale-up. This is the first qualitative study in Europe investigating experiences of HIVST among intervention users, and the first globally examining the experience of using blood-based HIVST. METHODS: Thirty-seven cisgender MSM SELPHI participants from across England and Wales were purposively recruited to the substudy, in which semi-structured interviews were used to explore testing history, HIVST experiences and intervention preferences. Interviews were audio-recorded, transcribed and analysed through a framework analysis. RESULTS: Men accessed the intervention because HIVST reduced barriers related to convenience, stigma and privacy concerns. Emotional responses had direct links to acceptability. Supportive intervention components increased engagement with testing and addressed supportive concerns. HIVST facilitated more frequent testing, with the potential to reduce sexually transmitted infection (STI) screening frequency. Substudy participants with an HIV-positive result (n = 2) linked to care promptly and reported very high acceptability. Minor adverse outcomes (n = 2; relationship discord and fainting) did not reduce acceptability. Ease of use difficulties were with the lancet and the test processing stage. CONCLUSIONS: Intervention components shaped acceptability, particularly in relation to overcoming a perceived lack of support. The intervention was broadly acceptable and usable; participants expressed an unexpected degree of enthusiasm for HIVST, including those with HIV-positive results and individuals with minor adverse outcomes.


Asunto(s)
Detección Precoz del Cáncer/métodos , Infecciones por VIH/diagnóstico , Homosexualidad Masculina/estadística & datos numéricos , Personas Transgénero/estadística & datos numéricos , Adolescente , Adulto , Países Desarrollados , Inglaterra , Estudios de Evaluación como Asunto , Femenino , Humanos , Entrevistas como Asunto , Masculino , Aceptación de la Atención de Salud , Juego de Reactivos para Diagnóstico , Autoevaluación , Gales , Adulto Joven
18.
Sci Rep ; 9(1): 16976, 2019 Nov 18.
Artículo en Inglés | MEDLINE | ID: mdl-31740683

RESUMEN

High-fidelity single-shot readout of spin qubits requires distinguishing states much faster than the T1 time of the spin state. One approach to improving readout fidelity and bandwidth (BW) is cryogenic amplification, where the signal from the qubit is amplified before noise sources are introduced and room-temperature amplifiers can operate at lower gain and higher BW. We compare the performance of two cryogenic amplification circuits: a current-biased heterojunction bipolar transistor circuit (CB-HBT), and an AC-coupled HBT circuit (AC-HBT). Both circuits are mounted on the mixing-chamber stage of a dilution refrigerator and are connected to silicon metal oxide semiconductor (Si-MOS) quantum dot devices on a printed circuit board (PCB). The power dissipated by the CB-HBT ranges from 0.1 to 1 µW whereas the power of the AC-HBT ranges from 1 to 20 µW. Referred to the input, the noise spectral density is low for both circuits, in the 15 to 30 fA/[Formula: see text] range. The charge sensitivity for the CB-HBT and AC-HBT is 330 µe/[Formula: see text] and 400 µe/[Formula: see text], respectively. For the single-shot readout performed, less than 10 µs is required for both circuits to achieve bit error rates below 10-3, which is a putative threshold for quantum error correction.

19.
Neurobiol Learn Mem ; 166: 107100, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31622665

RESUMEN

Sleep spindles have been implicated in motor learning in human subjects, but their occurrence, timing in relation to cortical slow oscillations, and relationship to offline gains in motor learning have not been examined in animal models. In this study, we recorded EEG over bilateral primary motor cortex in conjunction with EMG for 24 h following a period of either baseline handling or following rotarod motor learning to monitor sleep. We measured several biophysical properties of sleep spindles and their temporal coupling with cortical slow oscillations (SO, <1 Hz) and cortical delta waves (1-4 Hz). Following motor learning, we found an increase in spindles during an early period of NREM sleep (1-4 h) without changes to biophysical properties such as spindle power, peak frequency and coherence. In this same period of early NREM sleep, both SO and delta power increased after motor learning. Notably, a vast majority of spindles were associated with minimal SO power, but in the subset that were associated with significant SO power (>1 z-score above the population mean), spindle-associated SO power was greater in spindles following motor learning compared to baseline sleep. Also, we did not observe a group-level preferred phase in spindle-SO or spindle-delta coupling. While SO power alone was not predictive of motor performance in early NREM sleep, both spindle density and the difference in the magnitude of the mean resultant vector length of the phase angle for SO-associated spindles, a measure of its coupling precision, were positively correlated with offline change in motor performance. These findings support a role for sleep spindles and their coupling to slow oscillations in motor learning and establish a model in which spindle timing and the brain circuits that support offline plasticity can be mechanistically explored.


Asunto(s)
Ondas Encefálicas/fisiología , Encéfalo/fisiología , Aprendizaje/fisiología , Destreza Motora/fisiología , Sueño/fisiología , Animales , Electroencefalografía , Femenino , Masculino , Ratones
20.
Ultramicroscopy ; 207: 112833, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31494478

RESUMEN

We describe a method for obtaining the optimal design of a normal incidence Scanning Helium Microscope (SHeM). Scanning helium microscopy is a recently developed technique that uses low energy neutral helium atoms as a probe to image the surface of a sample without causing damage. After estimating the variation of source brightness with nozzle size and pressure, we perform a constrained optimisation to determine the optimal geometry of the instrument (i.e. the geometry that maximises intensity) for a given target resolution. For an instrument using a pinhole to form the helium microprobe, the source and atom optics are separable and Lagrange multipliers are used to obtain an analytic expression for the optimal parameters. For an instrument using a zone plate as the focal element, the whole optical system must be considered and a numerical approach has been applied. Unlike previous numerical methods for optimisation, our approach provides insight into the effect and significance of each instrumental parameter, enabling an intuitive understanding of effect of the SHeM geometry. We show that for an instrument with a working distance of 1 mm, a zone plate with a minimum feature size of 25 nm becomes the advantageous focussing element if the desired beam standard deviation is below about 300 nm.

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