Continuous wave terahertz detection using 1550 nm pumped nonlinear photoconductive GaAs metasurfaces.

Terahertz (THz) continuous wave (CW) spectroscopy systems can offer extremely high spectral resolution over the THz band by photo-mixing high-performance telecommunications-band (1530-1565 nm) lasers. However, typical THz CW detectors in these systems use narrow band-gap photoconductors, which require elaborate material growth and generate relatively large detector noise. Here we demonstrate that two-step photon absorption in a nano-structured low-temperature grown GaAs (LT-GaAs) metasurface which enables switching of photoconductivity within approximately one picosecond. We show that LT-GaAs can be used as an ultrafast photoconductor in CW THz detectors despite having a bandgap twice as large as the telecommunications laser photon energy. The metasurface design harnesses Mie modes in LT GaAs resonators, whereas metallic electrodes of THz detectors can be designed to support an additional photonic mode, which further increases photoconductivity at a desired wavelength.

PRIORITY Trial: Results from a feasibility randomised controlled trial of a psychoeducational intervention for parents to prevent disordered eating in children and young people with type 1 diabetes.

AIMS: Children and young people (CYP) with type 1 diabetes (T1D) are at increased risk of disordered eating. This study aimed to determine the feasibility and acceptability of a novel, theoretically informed, two-session psychoeducational intervention for parents to prevent disordered eating in CYP with T1D. METHODS: Parents of CYP aged 11-14 years with T1D were randomly allocated to the intervention or wait-list control group. Self-reported measures including the Diabetes Eating Problem Survey-Revised (DEPS-R), Problem Areas in Diabetes Parent Revised (PAID-PR), Child Eating Behaviour Questionnaire subscales (CEBQ), Warwick Edinburgh Mental Wellbeing Scale (WEMWBS), clinical outcomes (e.g. HbA1c, BMI, medication and healthcare utilisation) and process variables, were collected at baseline, 1-and 3-month assessments. Acceptability data were collected from intervention participants via questionnaire. RESULTS: Eighty-nine parents were recruited, which exceeded recruitment targets, with high intervention engagement and acceptability (<80% across domains). A signal of efficacy was observed across outcome measures with moderate improvements in the CEBQ subscale satiety responsiveness (d = 0.55, 95% CI 0.01, 1.08) and child's BMI (d = -0.56, 95% CI -1.09, 0.00) at 3 months compared with controls. Trends in the anticipated direction were also observed with reductions in disordered eating (DEPS-R) and diabetes distress (PAID-PR) and improvements in wellbeing (WEMWBS). CONCLUSIONS: This is the first study to have co-designed and evaluated a novel parenting intervention to prevent disordered eating in CYP with T1D. The intervention proved feasible and acceptable with encouraging effects. Preparatory work is required prior to definitive trial to ensure the most relevant primary outcome measure and ensure strategies for optimum outcome completion.

Near-Field Spectroscopy of Individual Asymmetric Split-Ring Terahertz Resonators.

Metamaterial resonators have become an efficient and versatile platform in the terahertz frequency range, finding applications in integrated optical devices, such as active modulators and detectors, and in fundamental research, e.g., ultrastrong light-matter investigations. Despite their growing use, characterization of modes supported by these subwavelength elements has proven to be challenging and it still relies on indirect observation of the collective far-field transmission/reflection properties of resonator arrays. Here, we present a broadband time-domain spectroscopic investigation of individual metamaterial resonators via a THz aperture scanning near-field microscope (a-SNOM). The time-domain a-SNOM allows the mapping and quantitative analysis of strongly confined modes supported by the resonators. In particular, a cross-polarized configuration presented here allows an investigation of weakly radiative modes. These results hold great potential to advance future metamaterial-based optoelectronic platforms for fundamental research in THz photonics.

Exploring the experiences and responses of siblings living with a brother or sister with obsessive compulsive disorder.

OBJECTIVES: The impact of having a child with diagnosed obsessive-compulsive disorder (OCD) can reportedly cause significant disruption to caregiver routines and negatively affect their mental health. Less is known about the impact to other first-degree relatives such as siblings due to limited research. It should not be assumed that findings in the caregiver literature can simply be applied to siblings. This study, therefore, aimed to explore the experiences and responses of cohabiting siblings of a brother or sister with an OCD diagnosis. METHOD: Eight participant siblings were recruited from a UK specialist OCD NHS clinic and interviewed via telephone about their experiences co-habiting with a brother or sister with OCD. Interviews were transcribed and subjected to interpretative phenomenological analysis (IPA). RESULTS: Two superordinate themes of 'OCD as a dangerous dictator' and the 'unifying/polarising influence of OCD on relationships' were interpreted from the eight participant experiences. Siblings spoke to OCD creating a dictatorial environment characterised by sibling loss, helplessness and adjustment. This fragile domestic environment seemingly pushed non-anxious siblings to the periphery of the family or conversely centralised their position through parentification. CONCLUSIONS: Many of the sibling experiences of frustration, distress avoidance, helplessness and symptom accommodation are mirrored in the burgeoning caregiver literature. Longitudinal studies are required to track sibling experiences over the course of their siblings OCD journey and expand our knowledge in this area. Counselling services, sibling support groups and inclusion in family assessment, formulation and treatment are possible avenues of exploration for siblings of those with an OCD diagnosis.

Terahertz Pulse Generation with Binary Phase Control in Nonlinear InAs Metasurface.

The effect of terahertz (THz) pulse generation has revolutionized broadband coherent spectroscopy and imaging at THz frequencies. However, THz pulses typically lack spatial structure, whereas structured beams are becoming essential for advanced spectroscopy applications. Nonlinear optical metasurfaces with nanoscale THz emitters can provide a solution by defining the beam structure at the generation stage. We develop a nonlinear InAs metasurface consisting of nanoscale optical resonators for simultaneous generation and structuring of THz beams. We find that THz pulse generation in the resonators is governed by optical rectification. It is more efficient than in ZnTe crystals, and it allows us to control the pulse polarity and amplitude, offering a platform for realizing binary-phase THz metasurfaces. To illustrate this capability, we demonstrate an InAs metalens, which simultaneously generates and focuses THz pulses. The control of spatiotemporal structure using nanoscale emitters opens doors for THz beam engineering and advanced spectroscopy and imaging applications.

Correction to "Terahertz Pulse Generation from GaAs Metasurfaces".

[This corrects the article DOI: 10.1021/acsphotonics.1c01908.].

Multi-family therapy for eating disorders across the lifespan: A systematic review and meta-analysis.

Eating disorders (EDs) have an estimated prevalence rate of 1%-5% across Europe. Effective adjunct interventions are needed to support the 20%-40% of families whose recovery requires additional support to first line approaches. This systematic review and meta-analysis aimed to establish whether multi-family therapy (MFT) improves the physical and psychological health of patients and family members. Searches were conducted in PsycINFO, MEDLINE, PubMed, EMBASE, CINAHL, and the Cochrane Library in March 2021. 15 studies (850 patients) met the inclusion criteria. Meta-analysis demonstrated MFT resulted in significant benefits in weight gain, ED symptoms, patients' and parents' depression symptoms, and parents' negative experiences of caregiving. However, significant improvements were only evident when comparisons were drawn before and after the intervention; these dissipated when MFT was compared to another intervention. There was no evidence MFT improves family functioning, positive aspects of caregiving, nor patient and parental anxiety. Intervention completion rates ranged from 86% to 100% indicating a high level of acceptability. Studies varied with regard to intervention length and structure, follow-up period, and outcome measures utilised; most were rated as moderate or weak in methodological quality. More rigorous and large scale randomised controlled trials are needed to fully assess the effectiveness of MFT.

Terahertz Pulse Generation from GaAs Metasurfaces.

Ultrafast optical excitation of select materials gives rise to the generation of broadband terahertz (THz) pulses. This effect has enabled the field of THz time-domain spectroscopy and led to the discovery of many physical mechanisms behind THz generation. However, only a few materials possess the required properties to generate THz radiation efficiently. Optical metasurfaces can relax stringent material requirements by shifting the focus onto the engineering of local electromagnetic fields to boost THz generation. Here we demonstrate the generation of THz pulses in a 160 nm thick nanostructured GaAs metasurface. Despite the drastically reduced volume, the metasurface emits THz radiation with efficiency comparable to that of a thick GaAs crystal. We reveal that along with classical second-order volume nonlinearity, an additional mechanism contributes strongly to THz generation in the metasurface, which we attribute to surface nonlinearity. Our results lay the foundation for engineering of semiconductor metasurfaces for efficient and versatile THz radiation emitters.

Development and Theoretical Underpinnings of the PRIORITY Intervention: A Parenting Intervention to Prevent Disordered Eating in Children and Young People With Type 1 Diabetes.

Children and young people (CYP) with type 1 diabetes (T1D) are twice as likely to develop disordered eating (T1DE) and clinical eating disorders than those without. This has significant implications for physical and mental health, with some eating disorders associated with repeated diabetic ketoacidosis and higher HbA1c levels, both of which are life threatening. There is currently limited psychological support for CYP and families with T1D but increasingly, policy and practice are suggesting disordered eating in T1D may be effectively prevented through psychological intervention. We describe the development and theoretical underpinnings of a preventative psychological intervention for parents of CYP aged 11-14, with T1D. The intervention was informed by psychological theory, notably the Information Motivation Behaviour Skills model and Behaviour Change Technique Taxonomy. The intervention was co-developed with an expert advisory group of clinicians, and families with T1D. The manualised intervention includes two online group workshops, and supplementary online materials. The intervention continues to evolve, and feasibility findings will inform how best to align the intervention with routine care in NHS diabetes teams. Early detection and intervention are crucial in preventing T1DE, and it is hoped that the current intervention can contribute to improving the psychological and physical wellbeing of young people and families managing T1D.

PaRent InterventiOn to pRevent dIsordered eating in children with TYpe 1 diabetes (PRIORITY): Study protocol for a feasibility randomised controlled trial.

AIMS: Increasing evidence suggests that children and young people with type 1 diabetes (T1D) are at greater risk of disordered eating compared to children without T1D. Disordered eating in T1D has been linked to impaired wellbeing, increased health service use and early mortality. To address this problem, we will co-develop a psycho-education intervention for parents of children and young people with T1D, informed by the Information Motivation Behavioural Skills model. METHODS: The objective of this study is to assess the feasibility and acceptability of the intervention compared to a waitlist control group using a feasibility randomised controlled trial (RCT) design. We aim to recruit 70 parents of children and young people with T1D (11-14 years), 35 in each arm. Those assigned to the intervention will be invited to participate in two workshops of 2 h each. Parents will be asked to complete outcome measures regarding eating habits, diabetes management, as well as a questionnaire based on the Information Motivation Behavioural Skills model which provides a theoretical foundation for the intervention. These will be completed at baseline, 1- and 3-month post-intervention. Children and young people will be asked to complete questionnaires on their eating behaviours at the same time intervals. Parents randomised to receive the intervention will be invited to take part in interviews to feedback on the intervention and research protocol acceptability. CONCLUSION: It is anticipated that the psycho-education intervention aimed at parents will help prevent the development of disordered eating in children and young people with T1D and improve parental wellbeing. The results of this feasibility trial will determine whether this intervention approach is acceptable to families living with T1D, and whether a definitive RCT of intervention effectiveness is justified. Qualitative findings will be used to refine the intervention and study protocols. TRIAL REGISTRATION: This protocol has been registered with ClinicalTrials.gov [Identifier: NCT04741568].

The experience of intolerance of uncertainty for parents of young people with a restrictive eating disorder.

PURPOSE: This study aimed to explore how parents of young people with a restrictive eating disorder (ED) experience and manage uncertainty. METHODS: Seventeen parents of young people with a restrictive ED were recruited from multi-family therapy groups run within a specialised ED clinic. Five focus groups were conducted asking parents about their experience of uncertainty both prior and after the onset of their child's illness. RESULTS: Data were analysed using interpretative phenomenological analysis which yielded seven superordinate themes. (1) Anorexia nervosa and uncertainty, (2) Positive and negative experiences of uncertainty (3), Helpful and unhelpful ways of coping with uncertainty, (4) Parent's self-efficacy and uncertainty (5), Needs of parents, (6) Parents' perceptions of intolerance of uncertainty in their children and (7) Impact of uncertainty on family life. CONCLUSION: Parents caring for young people with a restrictive ED exhibit a strong intolerance of uncertainty, particularly in relation to their child's illness. This 'negative uncertainty' was thought to reduce their confidence as parents in how they managed their child's ED. Targeting high levels of intolerance of uncertainty in parents caring for young people with an ED could be beneficial for supporting parents when faced with their child's illness, increasing parental self-efficacy, decreasing accommodating behaviours and ultimately contributing to improved treatment outcomes. LEVEL OF EVIDENCE: Level V: Opinions of authorities, based on descriptive studies, narrative reviews, clinical experience, or reports of expert committees.

Highly efficient terahertz photoconductive metasurface detectors operating at microwatt-level gate powers.

Despite their wide use in terahertz (THz) research and technology, the application spectra of photoconductive antenna (PCA) THz detectors are severely limited due to the relatively high optical gating power requirement. This originates from poor conversion efficiency of optical gate beam photons to photocurrent in materials with sub-picosecond carrier lifetimes. Here we show that using an ultra-thin (160 nm), perfectly absorbing low-temperature grown GaAs metasurface as the photoconductive channel drastically improves the efficiency of THz PCA detectors. This is achieved through perfect absorption of the gate beam in a significantly reduced photoconductive volume, enabled by the metasurface. This Letter demonstrates that sensitive THz PCA detection is possible using optical gate powers as low as 5 µW-three orders of magnitude lower than gating powers used for conventional PCA detectors. We show that significantly higher optical gate powers are not necessary for optimal operation, as they do not improve the sensitivity to the THz field. This class of efficient PCA THz detectors opens doors for THz applications with low gate power requirements.

Terahertz Detection with Perfectly-Absorbing Photoconductive Metasurface.

Terahertz (THz) photoconductive devices are used for generation, detection, and modulation of THz waves, and they rely on the ability to switch electrical conductivity on a subpicosecond time scale using optical pulses. However, fast and efficient conductivity switching with high contrast has been a challenge, because the majority of photoexcited charge carriers in the switch do not contribute to the photocurrent due to fast recombination. Here, we improve efficiency of electrical conductivity switching using a network of electrically connected nanoscale GaAs resonators, which form a perfectly absorbing photoconductive metasurface. We achieve perfect absorption without incorporating metallic elements, by breaking the symmetry of cubic Mie resonators. As a result, the metasurface can be switched between conductive and resistive states with extremely high contrast using an unprecedentedly low level of optical excitation. We integrate this metasurface with a THz antenna to produce an efficient photoconductive THz detector. The perfectly absorbing photoconductive metasurface opens paths for developing a wide range of efficient optoelectronic devices, where required optical and electronic properties are achieved through nanostructuring the resonator network.

The experience of intolerance of uncertainty for young people with a restrictive eating disorder: a pilot study.

PURPOSE: Research is consistently reporting elevated levels of intolerance of uncertainty (IU) in individuals with an eating disorder (ED). Less is known about the phenomenology of uncertainty for this clinical group. The present study aims to advance our understanding of the relationship between IU and restrictive EDs by providing insight into young people's subjective experiences of uncertainty. METHODS: Thirteen young people with a restrictive ED were recruited from multi-family therapy groups run within the Maudsley Centre for Child and Adolescent Eating Disorders at the South London and Maudsley NHS Foundation Trust. Three focus groups were conducted asking young people to discuss their views, experiences and coping strategies when faced with uncertainty. RESULTS: Data were analysed using interpretative phenomenological analysis which yielded five superordinate themes: (1) young people perceived uncertainty as something negative; (2) high levels of anxiety and stress were identified as primary responses to uncertainty; (3) ED behaviours were given a functional role in reducing uncertainty; (4) need to control various aspects of young peoples' lives was of high importance; (5) young people discussed how they struggled to find ways to cope with uncertainty and often used behaviours associated with the eating disorder psychopathology as coping strategies. CONCLUSION: Young people's experiences of what uncertainty is like for them revealed a dynamic interplay between ED symptoms and fear of uncertainty. Findings support IU as a relevant concept for young people suffering from a restrictive ED and indicate that further exploration of IU from both theoretical and clinical perspectives could be fruitful. LEVEL OF EVIDENCE: V.

MAESTROS: A Multiwavelength Time-Domain NIRS System to Monitor Changes in Oxygenation and Oxidation State of Cytochrome-C-Oxidase.

We present a multiwavelength, multichannel, time-domain near-infrared spectroscopy system named MAESTROS. This instrument can measure absorption and scattering coefficients and can quantify the concentrations of oxy- and deoxy-haemoglobin ([HbO2], [HHb]), and oxidation state of cytochrome-c-oxidase ([oxCCO]). This system is composed of a supercontinuum laser source coupled with two acousto-optic tuneable filters. The light is collected by four photomultipliers tubes, connected to a router to redirect the signal to a single time-correlated single-photon counting card. The interface between the system and the tissue is based on optical fibres. This arrangement allows us to resolve up to 16 wavelengths, within the range of 650-900 nm, at a sampling rate compatible with the physiology (from 0.5 to 2 Hz). In this paper, we describe the system and assess its performance based on two specifically designed protocols for photon migration instruments, the basic instrument protocol and nEUROPt protocols, and on a well characterized liquid phantom based on Intralipid and water. Then, the ability to resolve [HbO2 ], [HHb], and [oxCCO] is demonstrated on a homogeneous liquid phantom, based on blood for [HbO2], [HHb], and yeast for [oxCCO]. In the future, the system could be used to monitor brain tissue physiology.

A meta-analytic review of the relationship between family accommodation and OCD symptom severity.

Accommodation of obsessive compulsive disorder (OCD) symptoms by family members is common. This paper presents a systematic meta-analytic review on family accommodation and OCD symptom severity. Fourteen studies investigating the relationship between family accommodation and OCD symptoms were selected. The medium effect size of the relationship between family accommodation and OCD symptom severity was significant (r = .35; 95% CI: .23 to .47), based on a Hunter-Schmidt random effects model with a total of 849 participants. Although there was some evidence of publication bias, Rosenthal's fail-safe N suggested that 596 studies with zero effect would be needed to reduce the mean effect size to non-significant. Findings are discussed in the context of the limitations of the studies, and in particular the reliance on cross-sectional designs which impede causal conclusions. Future research to evaluate a family accommodation intervention in a randomized controlled design and using mediation analysis to explore change mechanisms is called for.

Facial affect recognition in anorexia nervosa: is obsessionality a missing piece of the puzzle?

OBJECTIVE: Socio-emotional difficulties are thought to be important maintaining factors of eating disorders. Several studies point to deficits in facial affect recognition in anorexia nervosa (AN). However, the majority of these studies fail to control for comorbidity and its effect on emotional processing. This study aims to explore how patients with AN recognize happiness and sadness in human faces, controlling for different comorbidities, namely anxiety, depression, and obsessive-compulsive symptoms. METHODS: Thirty patients with AN, and 40 healthy participants completed a facial emotion recognition task. This task measured discrimination accuracy, response bias and response time towards sad and happy faces presented at different durations (500 ms, 2000 ms). The associations between facial affect recognition and clinical symptoms and intelligence quotient were explored. RESULTS: Regression analysis showed that discrimination accuracy of sad faces presented for 500 ms was significantly associated with AN diagnosis, body mass index, and Obsessive-compulsive symptoms. However, the level of Obsessive-compulsive symptoms was the strongest predictor of a poor discrimination of briefly presented sad faces. CONCLUSIONS: Our results support previous studies that report emotional processing deficits in AN with obsessionality playing a pivotal role in this deficit.