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The central nervous system is the integrator of most of the actions of the animal and as such plays a vital rôle in the control of voluntary food intake. Much of the work to understand how intake is controlled has been carried out with rats but that which has been done with pigs is included. The first experiments used electrolytic lesions in the designation of the ‘hunger centre’ and the ‘satiety centre’. Recent work has identified the paraventricular nucleus as a sensing site for experimental manipulations. Chemical stimulation of the brain has also been carried out to try to gain understanding of the rôle of neurotransmitters. Noradrenaline (NA) stimulates intake when given into many sites. Serotonin (5-HT) inhibits intake and has been claimed to play a rôle in the selection of macronutrients but 5-HT must now be interpreted in the light of the existence of several different subtypes of 5-HT receptors. Dopamine appears to moderate the hedonic response of eating. Numerous peptides are active in the brain where their rôle as neuromodulators may be quite different from their function in the periphery and at least three types of opioid receptors are implicated with kappa antagonists producing the most potent facilitatory effects. Neuropeptide Y and peptide YY produce massive orexigenic effects which readily overcome peripheral satiety factors. The brain cannot control intake in isolation. It receives inputs in the blood stream, such as glucose, as well as via the nervous system, both from the special senses and from visceral organs such as stomach, intestines and liver. Taste and olfaction are important in diet selection and a specific appetite for protein has been demonstrated in the pig.
Identifying youth who may engage in future substance use could facilitate early identification of substance use disorder vulnerability. We aimed to identify biomarkers that predicted future substance use in psychiatrically un-well youth.
LASSO regression for variable selection was used to predict substance use 24.3 months after neuroimaging assessment in 73 behaviorally and emotionally dysregulated youth aged 13.9 (s.d. = 2.0) years, 30 female, from three clinical sites in the Longitudinal Assessment of Manic Symptoms (LAMS) study. Predictor variables included neural activity during a reward task, cortical thickness, and clinical and demographic variables.
Future substance use was associated with higher left middle prefrontal cortex activity, lower left ventral anterior insula activity, thicker caudal anterior cingulate cortex, higher depression and lower mania scores, not using antipsychotic medication, more parental stress, older age. This combination of variables explained 60.4% of the variance in future substance use, and accurately classified 83.6%.
These variables explained a large proportion of the variance, were useful classifiers of future substance use, and showed the value of combining multiple domains to provide a comprehensive understanding of substance use development. This may be a step toward identifying neural measures that can identify future substance use disorder risk, and act as targets for therapeutic interventions.
We summarise the first year of operation of the Medium Deep Survey - a key project of the HST. Two fields in the LMC are discussed and some preliminary scientific results presented. We also comment on image deconvolution for the extragalactic fields observed as part of the Medium Deep Survey.
Original studies published over the last decade regarding time trends in dementia report mixed results. The aims of the present study were to use linked administrative health data for the province of Saskatchewan for the period 2005/2006 to 2012/2013 to: (1) examine simultaneous temporal trends in annual age- and sex-specific dementia incidence and prevalence among individuals aged 45 and older, and (2) stratify the changes in incidence over time by database of identification.
Using a population-based retrospective cohort study design, data were extracted from seven provincial administrative health databases linked by a unique anonymized identification number. Individuals 45 years and older at first identification of dementia between April 1, 2005 and March 31, 2013 were included, based on case definition criteria met within any one of four administrative health databases (hospital, physician, prescription drug, and long-term care).
Between 2005/2006 and 2012/2013, the 12-month age-standardized incidence rate of dementia declined significantly by 11.07% and the 12-month age-standardized prevalence increased significantly by 30.54%. The number of incident cases decreased from 3,389 to 3,270 and the number of prevalent cases increased from 8,795 to 13,012. Incidence rate reductions were observed in every database of identification.
We observed a simultaneous trend of decreasing incidence and increasing prevalence of dementia over a relatively short 8-year time period from 2005/2006 to 2012/2013. These trends indicate that the average survival time of dementia is lengthening. Continued observation of these time trends is warranted given the short study period.
With HST and WFPC2, galaxies in the Medium Deep Survey can be reliably classified to magnitudes I814 ≲ 22.0 in the F814W band, at a mean redshift . The main result is the relatively high proportion (~40%) of objects which are in some way irregular or anomalous, and which are of relevance in understanding the origin of the familiar excess population of faint galaxies. These diverse objects include compact galaxies, apparently interacting pairs, galaxies with superluminous starforming regions and diffuse low surface brightness galaxies of various forms. The ‘irregulars’ and ‘peculiar’ galaxies contribute most of the excess counts in the I-band at our limiting magnitude, and may explain the ‘faint blue galaxy’ problem.
Commission 41 is one of the largest specialist components of the IAU. At the General Assembly in 1982 at Patras the number of ordinary members was increased from 79 to 86 as a testimony to the growing interest among astronomers in the history of their subject. At the same time the number of consulting members rose from 32 to 40, which shows that an increasing number of highly competent historians of science is engaged in research in the history of astronomy without being professional astronomers. However, many valuable contributions to the subject come from historians who are not members. In consequence, the principal purpose of Commission 41 is to serve as a link between all historians of astronomy whether they be members or not, by initiating research into particular areas, by disseminating new results, or simply by creating possibilities of personal contacts between scholars from different parts of the world. This is mainly achieved by meetings of various kinds.
The effect of Hybrid stage 1 palliation for hypoplastic left heart syndrome on right ventricular function is unknown. We sought to compare right ventricular function in normal neonates and those with hypoplastic left heart syndrome before Hybrid palliation and to assess the effect of Hybrid palliation on right ventricular function, using the right ventricular myocardial performance index and the ratio of systolic and diastolic durations.
We carried out a retrospective review of echocardiographic data on 23 infants with hypoplastic left heart syndrome who underwent Hybrid palliation and 35 normal controls. Data were acquired before Hybrid and after Hybrid palliation – post 1, 0–4 days; post 2, 1 week; post 3, 2–3 weeks; post 4, 1–1.5 months following Hybrid palliation.
Myocardial performance index and ratio of systolic and diastolic durations were higher in the pre-Hybrid hypoplastic left heart syndrome group (n=23) – 0.47±0.16 versus 0.25±0.07, p<0.001; 1.59±0.44 versus 1.09±0.14, p<0.0001 – compared with controls (n=35). There was no significant change in the myocardial performance index at any of the post-Hybrid time points. Ratio of systolic and diastolic durations increased significantly 2 weeks after Hybrid – post 3: 2.08±0.62 and post 4: 2.21±0.45 versus pre: 1.59±0.44, p=0.043 and 0.003. There were no significant differences in parameters between sub-groups of infants who died (n=10) and survivors (n=13).
Right ventricular myocardial performance index and ratio of systolic and diastolic durations were significantly higher in infants with hypoplastic left heart syndrome before intervention compared with controls. The ratio of systolic and diastolic durations increased significantly 2 weeks after Hybrid palliation. Our data suggest that infants with hypoplastic left heart syndrome have right ventricular dysfunction before intervention, which worsens over 2 weeks after Hybrid palliation.
Both maternal obesity and disordered mood have adverse effects on pregnancy outcome. We hypothesized that maternal very severe obesity (SO) is associated with increased anxiety and depression (A&D) symptoms during pregnancy, with adverse effects on gestational weight gain (GWG), postpartum mood and postpartum weight retention (PPWR) and explored any mediation by circulating glucocorticoids.
We measured A&D symptoms with validated questionnaires at weeks 17 and 28 of pregnancy and 3 months postpartum in 135 lean [body mass index (BMI) ⩽25 kg/m2] and 222 SO (BMI ⩾40 kg/m2) pregnant women. Fasting serum cortisol was measured by radioimmunoassay; GWG and PPWR were recorded.
A&D symptoms were higher in the SO group during pregnancy and postpartum despite adjusting for multiple confounders including previous mental health diagnosis (p < 0.05), and were non-linearly correlated with total GWG (anxiety R2 = 0.06, p = 0.037; depression R2 = 0.09, p = 0.001). In the SO group only, increased maternal anxiety (β = 0.33, p = 0.03) and depression (β = 0.19, p = 0.04) symptoms at week 17 of pregnancy were associated with increased PPWR, independent of total GWG and breastfeeding. Anxiety symptoms at week 28 of pregnancy, but not depression, were non-linearly correlated with serum cortisol level at week 36 of pregnancy (R2 = 0.06, p = 0.02). Cortisol did not mediate the link between A&D symptoms and GWG.
Maternal SO was associated with increased A&D symptoms, and with adverse effects on GWG and PPWR independent of circulating glucocorticoids. Strategies to optimize GWG and postpartum weight management in SO women should include assessment and management of maternal mood in early pregnancy.
The Kelvin–Helmholtz flow is a shearing instability that occurs at the interface between two fluids moving with different speeds. Here, the two fluids are each of finite depth, but are highly viscous. Consequently, their motion is caused by the horizontal speeds of the two walls above and below each fluid layer. The motion of the fluids is assumed to be governed by the Stokes approximation for slow viscous flow, and the fluid motion is thus responsible for movement of the interface between them. A linearized solution is presented, from which the decay rate and the group speed of the wave system may be obtained. The nonlinear equations are solved using a novel spectral representation for the streamfunctions in each of the two fluid layers, and the exact boundary conditions are applied at the unknown interface location. Results are presented for the wave profiles, and the behaviour of the curvature of the interface is discussed. These results are compared to the Boussinesq–Stokes approximation which is also solved by a novel spectral technique, and agreement between the results supports the numerical calculations.
Sleep loss produces abnormal increases in reward seeking but the mechanisms underlying this phenomenon are poorly understood. The present study examined the influence of one night of sleep deprivation on neural responses to a monetary reward task in a sample of late adolescents/young adults.
Using a within-subjects crossover design, 27 healthy, right-handed late adolescents/young adults (16 females, 11 males; mean age 23.1 years) underwent functional magnetic resonance imaging (fMRI) following a night of sleep deprivation and following a night of normal sleep. Participants' recent sleep history was monitored using actigraphy for 1 week prior to each sleep condition.
Following sleep deprivation, participants exhibited increased activity in the ventral striatum (VS) and reduced deactivation in the medial prefrontal cortex (mPFC) during the winning of monetary reward, relative to the same task following normal sleep conditions. Shorter total sleep time over the five nights before the sleep-deprived testing condition was associated with reduced deactivation in the mPFC during reward.
These findings support the hypothesis that sleep loss produces aberrant functioning in reward neural circuitry, increasing the salience of positively reinforcing stimuli. Aberrant reward functioning related to insufficient sleep may contribute to the development and maintenance of reward dysfunction-related disorders, such as compulsive gambling, eating, substance abuse and mood disorders.
Lyme borreliosis (LB) is the most common arthropod-borne disease of humans in the Northern hemisphere. In Europe, the causative agent, Borrelia burgdorferi sensu lato complex, is principally vectored by Ixodes ricinus ticks. The aim of this study was to identify environmental factors influencing questing I. ricinus nymph abundance and B. burgdorferi s.l. infection in questing nymphs using a large-scale survey across Scotland. Ticks, host dung and vegetation were surveyed at 25 woodland sites, and climatic variables from a Geographical Information System (GIS) were extracted for each site. A total of 2397 10 m2 transect surveys were conducted and 13 250 I. ricinus nymphs counted. Questing nymphs were assayed for B. burgdorferi s.l. and the average infection prevalence was 5·6% (range 0·8–13·9%). More questing nymphs and higher incidence of B. burgdorferi s.l. infection were found in areas with higher deer abundance and in mixed/deciduous compared to coniferous forests, as well as weaker correlations with season, altitude, rainfall and ground vegetation. No correlation was found between nymph abundance and infection prevalence within the ranges encountered. An understanding of the environmental conditions associated with tick abundance and pathogen prevalence may be used to reduce risk of exposure and to predict future pathogen prevalence and distributions under environmental changes.
Bulk ion implantations of AlxGa1-xAs (x = 0.6 or 0.85) were performed at 77 K with 1.5 MeV Kr+, 1 MeV Ar+ or 1.5 MeV++ ions, and the resulting damage state examined by using Rutherford backscattering spectrometry-channeling at 77 K and 293 K and transmission electron microscopy at 300 K. Amorphization of a portion of the A1xGa1-x As layer occurred at 77 K only for the 1.5 MeV Kr+ implantation, although the dose required to cause amorphization was higher for the higher Al content alloy. TRIM calculations[10–11] show that with this implantation the density of high energy density cascades varies as a function of depth through the layer and that these are superimposed on a high, uniform density of defects. Comparison of the ion channeling spectra at 77 K and 293 K shows that recovery occurs over a portion of the layer in the Al0.6Ga0.4As but is not detected in the A10.85Ga0.15As layer. In both alloys, the room temperature microstructure consists of an amorphous and a crystalline region. The amorphous region extends from the deeper AlxGa1-xAs/GaAs interface into the layer, and is separated from the crystalline material by a crystalline region containing planar defects. The difference between the alloys is in the extent of this latter region, which decreases in width with increasing Al content. These results will be used to examine current models for amorphization in the AlxGa1-xAs system.
Depression is a leading cause of worldwide disability. Adolescence represents a key developmental window in which rates of this disorder increase markedly. Children with an anxiety disorder show a particular risk of developing depression during adolescence.
We present and review evidence for a developmental model that considers the intersection of two vulnerabilities relevant to the trajectory from anxiety to depression: difficulties in response to potential social evaluation and changes in reward processing at puberty.
Evidence suggests that these vulnerabilities (a) have been associated with depression, (b) are likely to be problematic in many, but not all, anxious youth, and (c) may be exacerbated by maturational processes that occur around pubertal development in ways that can create a negative spiral into a depressive disorder.
We discuss the possibility that early intervention strategies targeting key aspects of these vulnerabilities could alter the trajectory away from depression for many anxious youth.
The increasing prevalence of obesity among youth has elicited calls for schools to become more active in promoting healthy weight. The present study examined associations between various aspects of school food environments (specifically the availability of snack- and beverage-vending machines and the presence of snack and beverage logos) and students’ weight status, as well as potential influences of indices of diet and food behaviours.
A cross-sectional, self-administered web-based survey. A series of multinomial logistic regressions with generalized estimating equations (GEE) were constructed to examine associations between school environment variables (i.e. the reported presence of beverage- and snack-vending machines and logos) and self-reported weight- and diet-related behaviours.
Secondary schools in Alberta, Canada.
A total of 4936 students from grades 7 to 10.
The presence of beverage-vending machines in schools was associated with the weight status of students. The presence of snack-vending machines and logos was associated with students’ frequency of consuming vended goods. The presence of snack-vending machines and logos was associated with the frequency of salty snack consumption.
The reported presence of snack- and beverage-vending machines and logos in schools is related to some indices of weight status, diet and meal behaviours but not to others. The present study supported the general hypothesis that the presence of vending machines in schools may affect students’ weight through increased consumption of vended goods, but notes that the frequency of ‘junk’ food consumption does not seem to be related to the presence of vending machines, perhaps reflecting the ubiquity of these foods in the daily lives of students.
Porous silica glasses have been prepared using an HF-catalyzed tetraethoxysilane(TEOS)-ethanol-water formulation. The optical and physical properties of these glasses, which find use as host matrices for optical organic dyes, can be further improved with the addition of 1,3,5-trioxane to the sol-gel chemical system. In order to understand the effect of trioxane, the time-dependent concentrations of the species involved in TEOS hydrolysis and condensation have been followed by Raman, FT-IR, and NMR spectroscopie methods in both HF-catalyzed TEOS-ethanol-water systems with and without trioxane.
The development of the damage structure produced in (100) GaAs/Al0.6Ga0.4As/GaAs by 1 MeV Kr+ ion irradiation at 77 and 293 K has been investigated by RBS channeling and cross-sectional high-resolution TEM techniques. Following an implantation to a dose of 1014 ions cm-2 at 77 K, RBS channeling spectra indicate that the Al0.6Ga0.4 layer contained a high defect density and was possibly amorphous. Warming to room temperature resulted in a change in the channeling spectrum, which indicated that the damage in the Al0.6Ga0.4As layer had partially recovered. The degree of recovery was greatest at the GaAs/ Al0.6Ga0.4As interface, and decreased with increasing depth. TEM observations show the damage in the Al0.6Ga0.4As to be comprised of planar defects, the density of which increases with depth, and an amorphous layer at the bottom interface. This difference in the damage distribution is consistent with the asymmetry in the channeling spectrum. A model based on the depth variation of cascade density is proposed to account for the observations.