Symmetry-breaking and chaos in electron transport in semiconductor superlattices

We study the motion of electrons in a single miniband of a semiconductor superlattice driven by THz electric field polarized along the growth direction. We work in the semiclassical balance-equation model, including different elastic and inelastic scattering rates, and incorporating the self-consistent electric field generated by electron motion. We explore regions of complex dynamics, which can include chaotic behaviour and symmetry-breaking. We estimate the magnitudes of dc current and dc voltage that spontaneously appear in regions of broken-symmetry for parameters characteristic of modern semiconductor superlattices. This work complements PRL 80(1998)2669 [ cond-mat/9709026 ].Comment: 4 pages, 3 figures, RevTEX, EPS

Low energy availability assessed by a sport-specific questionnaire and clinical interview indicative of bone health, endocrine profile and cycling performance in competitive male cyclists

Objectives To evaluate the efficacy of a sport-specific energy availability (EA) questionnaire, combined with clinical interview, for identifying male athletes at risk of developing bone health, endocrine and performance consequences of relative energy deficiency in sports (RED-S). Methods Fifty competitive male road cyclists, recruited through links of participants in a pilot study, were assessed by a newly developed sport-specific questionnaire and clinical interview (SEAQ-I) and received dual energy X-ray absorptiometry (DXA) bone mineral density (BMD) and body composition scans and blood tests for endocrine markers. Results Low EA as assessed using the SEAQ-I, was observed in 28% of cyclists. Low lumbar spine BMD (Z-score<−1.0) was found in 44% of cyclists. EA was the most significant determinant of lumbar spine BMD Z-score (p<0.001). Among low EA cyclists, lack of previous load-bearing sport was associated with the lowest BMD (p=0.013). Low EA was associated with reduced total percentage fat (p<0.019). The 10 cyclists with chronic low EA had lower levels of testosterone compared with those having adequate EA (p=0.024). Mean vitamin D concentration was below the level recommended for athletes (90  nmol/L). Training loads were positively associated with power-to-weight ratios, assessed as 60  min functional threshold power (FTP) per kg (p<0.001). Percentage body fat was not significantly linked to cycling performance. Conclusions This study demonstrates that a SEAQ-I is effective for identifying male road cyclists with acute intermittent and chronic sustained low EA. Cyclists with low EA, particularly in the long-term, displayed adverse quantifiable measures of bone, endocrinology and performance consequences of RED-S

Calcutta Botanic Garden and the colonial re-ordering of the Indian environment

This article examines three hand-painted colour maps that accompanied the annual report of the Calcutta Botanic Garden for 1846 to illustrate how the Garden’s layout, uses and functions had changed over the previous 30 years. The evolution of the Calcutta Botanic Garden in the first half of the nineteenth-century reflects a wider shift in attitudes regarding the relationship between science, empire and the natural world. On a more human level the maps result from, and illustrate, the development of a vicious personal feud between the two eminent colonial botanists charged with superintending the garden in the 1840s

Spontaneous DC Current Generation in a Resistively Shunted Semiconductor Superlattice Driven by a TeraHertz Field

We study a resistively shunted semiconductor superlattice subject to a high-frequency electric field. Using a balance equation approach that incorporates the influence of the electric circuit, we determine numerically a range of amplitude and frequency of the ac field for which a dc bias and current are generated spontaneously and show that this region is likely accessible to current experiments. Our simulations reveal that the Bloch frequency corresponding to the spontaneous dc bias is approximately an integer multiple of the ac field frequency.Comment: 8 pages, Revtex, 3 Postscript figure

While We Waited: Incidence and Predictors of Falls in Older Adults With Cataract.

PURPOSE: Strong evidence indicates an increased fall risk associated with cataract. Although cataract surgery can restore sight, lengthy wait times are common for public patients in many high-income countries. This study reports incidence and predictors of falls in older people with cataract during their surgical wait. METHODS: Data from a prospective study of falls in adults aged ≥65 years who were awaiting cataract surgery in public hospitals in Australia were analyzed. Participants underwent assessment of vision, health status, and physical function, and recalled falls in the previous 12 months. Falls were self-reported prospectively during the surgical wait. RESULTS: Of 329 participants, mean age was 75.7 years; 55.2% were female. A total of 267 falls were reported by 101 (30.7%) participants during the surgical wait (median observation time, 176 days): an incidence of 1.2 falls per person-year (95% confidence interval [CI] 1.0-1.3). Greater walking activity (incidence rate ratio [IRR] 1.06, 95% CI 1.01-1.10; P = 0.02, per additional hour/week), poorer health-related quality of life (IRR 1.12, 95% CI 1.05-1.20; P < 0.001, per 5-unit decrease), and a fall in the prior 12 months (IRR 2.48, 95% CI 1.57-3.93; P < 0.001) were associated with incident falls. No visual measure independently predicted fall risk. More than one-half (51.7%) of falls were injurious. CONCLUSIONS: We found a substantial rate of falls and fall injury in older adults with cataract who were awaiting surgery. Within this relatively homogenous cohort, measures of visual function alone inadequately predicted fall risk. Assessment of exposure to falls through physical activity frequency may prove valuable in identifying those more likely to fall during the surgical wait

While We Waited: Incidence and Predictors of Falls in Older Adults With Cataract

Purpose: Strong evidence indicates an increased fall risk associated with cataract. Although cataract surgery can restore sight, lengthy wait times are common for public patients in many high-income countries. This study reports incidence and predictors of falls in older people with cataract during their surgical wait. Methods: Data from a prospective study of falls in adults aged ≥65 years who were awaiting cataract surgery in public hospitals in Australia were analyzed. Participants underwent assessment of vision, health status, and physical function, and recalled falls in the previous 12 months. Falls were self-reported prospectively during the surgical wait. Results: Of 329 participants, mean age was 75.7 years; 55.2% were female. A total of 267 falls were reported by 101 (30.7%) participants during the surgical wait (median observation time, 176 days): an incidence of 1.2 falls per person-year (95% confidence interval [CI] 1.0–1.3). Greater walking activity (incidence rate ratio [IRR] 1.06, 95% CI 1.01–1.10; P = 0.02, per additional hour/week), poorer health-related quality of life (IRR 1.12, 95% CI 1.05–1.20; P < 0.001, per 5-unit decrease), and a fall in the prior 12 months (IRR 2.48, 95% CI 1.57–3.93; P < 0.001) were associated with incident falls. No visual measure independently predicted fall risk. More than one-half (51.7%) of falls were injurious. Conclusions: We found a substantial rate of falls and fall injury in older adults with cataract who were awaiting surgery. Within this relatively homogenous cohort, measures of visual function alone inadequately predicted fall risk. Assessment of exposure to falls through physical activity frequency may prove valuable in identifying those more likely to fall during the surgical wait

The impact of assisted reproductive technology treatments on maternal and offspring outcomes in singleton pregnancies: A review of systematic reviews

Objectives: Assisted reproductive technology (ART) treatments are commonly used to aid conception in subfertile couples. We aimed to evaluate the risks of adverse maternal and offspring outcomes in singleton pregnancy conceived with different ART treatments and techniques. / Evidence review: We searched MEDLINE, EMBASE, CENTRAL and HTA until December 2020 for all systematic reviews evaluating adverse outcomes in pregnancies conceived with various ART techniques, autologous or donor gametes, and embryo development stages. We assessed review quality using the AMSTAR2 tool risk (RR) or odds ratio (OR) with 95% confidence intervals (CI) from the top quality reviews for each of the outcomes of interest across the identified ART treatments and population subgroups. / Results: We included 24 systematic reviews, most reported on observational studies. Compared to spontaneous conception, ART pregnancies had a higher risk of placenta previa (PP) (RR 3.71, 95%CI 2.67-5.16), antepartum haemorrhage (APH) (RR 2.11, 95%CI 1.86-2.38), preterm birth (PTB) (RR 1.71, 95%CI 1.59-1.83), very preterm birth (VPTB) (RR 2.12, 95%CI 1.73-2.59), small for gestational age (SGA) (RR 1.35, 95%CI 1.20-1.52), low birthweight (LBW) (RR 1.61, 95%CI 1.49-1.75) and very low birthweight (VLBW) (RR 2.12, 95%CI 1.84-2.43). Frozen vs fresh embryo transfer was associated with a lower risk for PTB (RR 0.90, 95%CI 0.84-0.97), SGA (RR 0.61, 95%CI 0.56-0.67), LBW (RR 0.72, 95%CI 0.67-0.77) and VLBW (RR 0.76, 95%CI 0.69–0.82). Embryo transfer at blastocyst vs cleavage showed higher risk for PTB (RR 1.10, 95%CI 1.01-1.20) and large for gestational age (LGA) (RR 1.12, 95%CI 1.03-1.21) with lower risk for SGA (RR 0.84, 95%CI 0.76-0.92). Using donor vs autologous oocytes increased the odds of PTB (OR 1.57, 95%CI 1.33-1.86), LBW (OR 1.94, 95%CI 1.10-3.41) and VLBW (OR 1.37, 95%CI 1.22–1.54) as well as maternal complications (postpartum haemorrhage OR 1.96, 95% CI 1.20-3.20, gestational diabetes OR 1.27 95%CI 1.03-1.56, hypertensive disorders of pregnancy OR 2.63, 95%CI 2.17-3.18, and caesarean section OR 2.28, 95%CI 2.14-2.42). / Conclusions: ART treatments are associated with increased risks of adverse maternal and offspring outcomes, especially with donor oocytes. The characteristics of ART treatment should be incorporated into prenatal care planning to mitigate those risks

Resonant Photon-Assisted Tunneling Through a Double Quantum Dot: An Electron Pump From Spatial Rabi Oscillations

The time average of the fully nonlinear current through a double quantum dot, subject to an arbitrary combination of ac and dc voltages, is calculated exactly using the Keldysh nonequilibrium Green function technique. When driven on resonance, the system functions as an efficient electron pump due to Rabi oscillation between the dots. The pumping current is maximum when the coupling to the leads equals the Rabi frequency.Comment: 6 pages, REVTEX 3.0, 3 postscript figure

Frequency of coexistent eye diseases and cognitive impairment or dementia: a systematic review and meta-analysis

Objective: We aim to quantify the co-existence of age-related macular degeneration (AMD), glaucoma, or diabetic retinopathy (DR) and cognitive impairment or dementia. Method: MEDLINE, EMBASE, PsycINFO and CINAHL were searched (to June 2020). Observational studies reporting incidence or prevalence of AMD, glaucoma, or DR in people with cognitive impairment or dementia, and of cognitive impairment or dementia among people with AMD, glaucoma, or DR were included. Results: Fifty-six studies (57 reports) were included but marked by heterogeneities in the diagnostic criteria or definitions of the diseases, study design, and case mix. Few studies reported on the incidence. Evidence was sparse but consistent in individuals with mild cognitive impairment where 7.7% glaucoma prevalence was observed. Prevalence of AMD and DR among people with cognitive impairment ranged from 3.9% to 9.4% and from 11.4% to 70.1%, respectively. Prevalence of AMD and glaucoma among people with dementia ranged from 1.4 to 53% and from 0.2% to 25.9%, respectively. Prevalence of DR among people with dementia was 11%. Prevalence of cognitive impairment in people with AMD, glaucoma, and DR ranged from 8.4% to 52.4%, 12.3% to 90.2%, and 3.9% to 77.8%, respectively, and prevalence of dementia in people with AMD, glaucoma and DR ranged from 9.9% to 62.6%, 2.5% to 3.3% and was 12.5%, respectively. Conclusions: Frequency of comorbid eye disease and cognitive impairment or dementia varied considerably. While more population-based estimations of the co-existence are needed, interdisciplinary collaboration might be helpful in the management of these conditions to meet healthcare needs of an ageing population. Trial registration: PROSPERO registration: CRD42020189484

Do carers of adolescents at first episode psychosis have distinctive psychological needs? A pilot exploration

Background: Carers of patients experiencing first episode psychosis (FEP) are at an increased risk of mental and physical health problems themselves. However, little is known about how the psychological needs of carers may differ between those caring for an adolescent versus an adult who has FEP. Aims: This pilot study aimed to explore any differences in the psychological needs of carers caring for adolescents versus adults with FEP. Methods: We surveyed 254 carers of 198 FEP patients (34 carers of adolescents of 24 FEP adolescent patients). Carers completed self-report measures of anxiety, depression, burnout, subjective burden, coping, and key illness beliefs. The sample was divided according to whether the patient was under (adolescent) or over (adult) age 18, and analysed using mixed model logistic regressions. Results: Compared to the carers of adult patients, carers of adolescents were more than twice as likely (12% vs. 30%) to experience overall burnout syndrome (all three domains), and to develop it much quicker (19.4 vs. 10.1 months). They were also more likely to adopt behavioural disengagement avoidance as a form of coping. However, there was no difference between carers in terms of anxiety, depression, beliefs and subjective burden. For carers of adolescents, burnout was independently predicted by: a negative belief about the consequences of psychosis for the adolescent patient and an incoherent understanding of the patient’s mental health. Conclusions: If our findings can be replicated in a larger sample, then Rapid-Onset-Burnout-Syndrome (ROBS) is a particular problem in carers of adolescents at FEP, suggesting a need for routine screening and possible prophylactic intervention. Carers of adolescent’s use of behavioural escape coping maybe also require early intervention. Theoretically, consideration could be given to the development of an adolescent sub-branch to the cognitive model of caregiving