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Current adolescent substance use risk models have inadequately predicted use for African Americans, offering limited knowledge about differential predictability as a function of developmental period. Among a sample of 500 African American youth (ages 11–21), four risk indices (i.e., social risk, attitudinal risk, intrapersonal risk, and racial discrimination risk) were examined in the prediction of alcohol, marijuana, and cigarette initiation during early (ages 11–13), mid (ages 16–18), and late (ages 19–21) adolescence. Results showed that when developmental periods were combined, racial discrimination was the only index that predicted initiation for all three substances. However, when risk models were stratified based on developmental period, variation was found within and across substance types. Results highlight the importance of racial discrimination in understanding substance use initiation among African American youth and the need for tailored interventions based on developmental stage.
Objectives: Studies of neurocognitively elite older adults, termed SuperAgers, have identified clinical predictors and neurobiological indicators of resilience against age-related neurocognitive decline. Despite rising rates of older persons living with HIV (PLWH), SuperAging (SA) in PLWH remains undefined. We aimed to establish neuropsychological criteria for SA in PLWH and examined clinically relevant correlates of SA. Methods: 734 PLWH and 123 HIV-uninfected participants between 50 and 64 years of age underwent neuropsychological and neuromedical evaluations. SA was defined as demographically corrected (i.e., sex, race/ethnicity, education) global neurocognitive performance within normal range for 25-year-olds. Remaining participants were labeled cognitively normal (CN) or impaired (CI) based on actual age. Chi-square and analysis of variance tests examined HIV group differences on neurocognitive status and demographics. Within PLWH, neurocognitive status differences were tested on HIV disease characteristics, medical comorbidities, and everyday functioning. Multinomial logistic regression explored independent predictors of neurocognitive status. Results: Neurocognitive status rates and demographic characteristics differed between PLWH (SA=17%; CN=38%; CI=45%) and HIV-uninfected participants (SA=35%; CN=55%; CI=11%). In PLWH, neurocognitive groups were comparable on demographic and HIV disease characteristics. Younger age, higher verbal IQ, absence of diabetes, fewer depressive symptoms, and lifetime cannabis use disorder increased likelihood of SA. SA reported increased independence in everyday functioning, employment, and health-related quality of life than non-SA. Conclusions: Despite combined neurological risk of aging and HIV, youthful neurocognitive performance is possible for older PLWH. SA relates to improved real-world functioning and may be better explained by cognitive reserve and maintenance of cardiometabolic and mental health than HIV disease severity. Future research investigating biomarker and lifestyle (e.g., physical activity) correlates of SA may help identify modifiable neuroprotective factors against HIV-related neurobiological aging. (JINS, 2019, 25, 507–519)
Loneliness and social networks have been extensively studied in relation to cognitive impairments, but how they interact with each other in relation to cognition is still unclear. This study aimed at exploring the interaction of loneliness and various types of social networks in relation to cognition in older adults.
a cross-sectional study.
497 older adults with normal global cognition were interviewed.
Loneliness was assessed with Chinese 6-item De Jong Gierverg’s Loneliness Scale. Confiding network was defined as people who could share inner feelings with, whereas non-confiding network was computed by subtracting the confiding network from the total network size. Cognitive performance was expressed as a global composite z-score of Cantonese version of mini mental state examination (CMMSE), Categorical verbal fluency test (CVFT) and delayed recall. Linear regression was used to test the main effects of loneliness and the size of various networks, and their interaction on cognitive performance with the adjustment of sociodemographic, physical and psychological confounders.
Significant interaction was found between loneliness and non-confiding network on cognitive performance (B = .002, β = .092, t = 2.099, p = .036). Further analysis showed a significant interaction between loneliness and the number of family members in non-confiding network on cognition (B = .021, β = .119, t = 2.775, p = .006).
Results suggested that a non-confiding relationship with family members might put lonely older adults at risk of cognitive impairment. Our study might have implications on designing psychosocial intervention for those who are vulnerable to loneliness as an early prevention of neurocognitive impairments.
In an effort to optimize patient outcomes, considerable attention is being devoted to identifying patient characteristics associated with major depressive disorder (MDD) and its responsiveness to treatment. In the current study, we extend this work by evaluating whether early change in these sensitivities is associated with response to antidepressant treatment for MDD.
Participants included 210 patients with MDD who were treated with 8 weeks of escitalopram and 112 healthy comparison participants. Of the original 210 patients, 90 non-responders received adjunctive aripiprazole for an additional 8 weeks. Symptoms of depression and anhedonia were assessed at the beginning of treatment and 8 weeks later in both samples. Reward and punishment sensitivity were assessed using the BIS/BAS scales measured at the initiation of treatment and 2 weeks later.
Individuals with MDD exhibited higher punishment sensitivity and lower reward sensitivity compared with healthy comparison participants. Change in reward sensitivity during the first 2 weeks of treatment was associated with improved depressive symptoms and anhedonia following 8 weeks of treatment with escitalopram. Similarly, improvement in reward responsiveness during the first 2 weeks of adjunctive therapy with aripiprazole was associated with fewer symptoms of depression at post-treatment.
Findings highlight the predictive utility of early change in reward sensitivity during antidepressant treatment for major depression. In a clinical setting, a lack of change in early reward processing may signal a need to modify a patient's treatment plan with alternative or augmented treatment approaches.
We report the discovery in the Greenland ice sheet of a discrete layer of free nanodiamonds (NDs) in very high abundances, implying most likely either an unprecedented influx of extraterrestrial (ET) material or a cosmic impact event that occurred after the last glacial episode. From that layer, we extracted n-diamonds and hexagonal diamonds (lonsdaleite), an accepted ET impact indicator, at abundances of up to about 5×106 times background levels in adjacent younger and older ice. The NDs in the concentrated layer are rounded, suggesting they most likely formed during a cosmic impact through some process similar to carbon-vapor deposition or high-explosive detonation. This morphology has not been reported previously in cosmic material, but has been observed in terrestrial impact material. This is the first highly enriched, discrete layer of NDs observed in glacial ice anywhere, and its presence indicates that ice caps are important archives of ET events of varying magnitudes. Using a preliminary ice chronology based on oxygen isotopes and dust stratigraphy, the ND-rich layer appears to be coeval with ND abundance peaks reported at numerous North American sites in a sedimentary layer, the Younger Dryas boundary layer (YDB), dating to 12.9 ± 0.1 ka. However, more investigation is needed to confirm this association.
It has been suggested that most of the primeval galactic globular clusters have been dissociated by encounters with molecular clouds, and by tidal effects in the vicinity of the galactic center; their stellar remnants would move preserving some memory of their original kinematical parameters and might resemble the well-known population I moving clusters. However it has been shown, by direct numerical integration, that a significant fraction of the halo stars have chaotic orbits and many others reach high z-values; hence the usual criterium of identifying group members by the similarity of their V-velocities breaks down. Instead, we use the constancy of the integrals of motion, i.e. the total energy and the z- component of the angular momentum, as well as the metallicity [Fe/H], as the identifying parameters for group membership of a given star. From the analysis of the metallicities and the integrals of motion of 206 halo stars, we have been able to identify several halo moving groups.
Using the uvby – β data of Schuster and Nissen (1988) to calculate photometric distances and using the galactic potentials of Allen and Martos (1986) and Allen and Santillán (1991), galactic orbits have been integrated for 615 halo and high-velocity disk stars. Correlations between orbital characteristics, metallicities, and ages are being studied. For the 206 halo stars of this sample, a particularly high percentage of the orbits (35-50%) show some chaotic behavior, due mainly to their low angular momenta which lead to small (< 1 Kpc) perigalactic distances. The newer potential of Allen and Santillán, which includes a spherical central bulge rather than a central mass point, gives the higher percentage of chaotic orbits. The effects of this chaos upon chemical gradients and upon the dynamical structure of the halo are being investigated.
Objectives: The present study examined differences in neurocognitive outcomes among non-Hispanic Black and White stroke survivors using the NIH Toolbox-Cognition Battery (NIHTB-CB), and investigated the roles of healthcare variables in explaining racial differences in neurocognitive outcomes post-stroke. Methods: One-hundred seventy adults (91 Black; 79 White), who participated in a multisite study were included (age: M=56.4; SD=12.6; education: M=13.7; SD=2.5; 50% male; years post-stroke: 1–18; stroke type: 72% ischemic, 28% hemorrhagic). Neurocognitive function was assessed with the NIHTB-CB, using demographically corrected norms. Participants completed measures of socio-demographic characteristics, health literacy, and healthcare use and access. Stroke severity was assessed with the Modified Rankin Scale. Results: An independent samples t test indicated Blacks showed more neurocognitive impairment (NIHTB-CB Fluid Composite T-score: M=37.63; SD=11.67) than Whites (Fluid T-score: M=42.59, SD=11.54; p=.006). This difference remained significant after adjusting for reading level (NIHTB-CB Oral Reading), and when stratified by stroke severity. Blacks also scored lower on health literacy, reported differences in insurance type, and reported decreased confidence in the doctors treating them. Multivariable models adjusting for reading level and injury severity showed that health literacy and insurance type were statistically significant predictors of the Fluid cognitive composite (p<.001 and p=.02, respectively) and significantly mediated racial differences on neurocognitive impairment. Conclusions: We replicated prior work showing that Blacks are at increased risk for poorer neurocognitive outcomes post-stroke than Whites. Health literacy and insurance type might be important modifiable factors influencing these differences. (JINS, 2017, 23, 640–652)
Bartonellae are blood- and vector-borne Gram-negative bacteria, recognized as emerging pathogens. Whole-blood samples were collected from 58 free-ranging lions (Panthera leo) in South Africa and 17 cheetahs (Acinonyx jubatus) from Namibia. Blood samples were also collected from 11 cheetahs (more than once for some of them) at the San Diego Wildlife Safari Park. Bacteria were isolated from the blood of three (5%) lions, one (6%) Namibian cheetah and eight (73%) cheetahs from California. The lion Bartonella isolates were identified as B. henselae (two isolates) and B. koehlerae subsp. koehlerae. The Namibian cheetah strain was close but distinct from isolates from North American wild felids and clustered between B. henselae and B. koehlerae. It should be considered as a new subspecies of B. koehlerae. All the Californian semi-captive cheetah isolates were different from B. henselae or B. koehlerae subsp. koehlerae and from the Namibian cheetah isolate. They were also distinct from the strains isolated from Californian mountain lions (Felis concolor) and clustered with strains of B. koehlerae subsp. bothieri isolated from free-ranging bobcats (Lynx rufus) in California. Therefore, it is likely that these captive cheetahs became infected by an indigenous strain for which bobcats are the natural reservoir.
The evidence underpinning the developmental origins of health and disease (DOHaD) is overwhelming. As the emphasis shifts more towards interventions and the translational strategies for disease prevention, it is important to capitalize on collaboration and knowledge sharing to maximize opportunities for discovery and replication. DOHaD meetings are facilitating this interaction. However, strategies to perpetuate focussed discussions and collaborations around and between conferences are more likely to facilitate the development of DOHaD research. For this reason, the DOHaD Society of Australia and New Zealand (DOHaD ANZ) has initiated themed Working Groups, which convened at the 2014–2015 conferences. This report introduces the DOHaD ANZ Working Groups and summarizes their plans and activities. One of the first Working Groups to form was the ActEarly birth cohort group, which is moving towards more translational goals. Reflecting growing emphasis on the impact of early life biodiversity – even before birth – we also have a Working Group titled Infection, inflammation and the microbiome. We have several Working Groups exploring other major non-cancerous disease outcomes over the lifespan, including Brain, behaviour and development and Obesity, cardiovascular and metabolic health. The Epigenetics and Animal Models Working Groups cut across all these areas and seeks to ensure interaction between researchers. Finally, we have a group focussed on ‘Translation, policy and communication’ which focusses on how we can best take the evidence we produce into the community to effect change. By coordinating and perpetuating DOHaD discussions in this way we aim to enhance DOHaD research in our region.
This triennial report (1996-1999) reviews the subject from a somewhat personal angle, mostly related to binary star formation and young binary star populations – a subject whose time had come in the early 1990s and is now in full swing.
Many astronomers have searched for binary systems among main-sequence stars, and two large-scale surveys published in 1991 and 1992 have already become classics. Well before they became famous for finding extrasolar planets (see below), observing teams led by Michel Mayor (Geneva Observatory) and Geoffrey Marcy (San Francisco State Univ., now Univ. of Calif, at Berkeley) spent many years searching for low-mass stellar companions of nearby stars. The late Antoine Duquennoy and Mayor surveyed all solar-type dwarfs (spectral types F7 through G9) within 20 pc of the Sun, while Debra Fischer and Marcy studied stars with somewhat lower mass (M dwarfs) slightly nearer to the Sun.
Our knowledge of the universe comes from recording the photon and particle fluxes incident on the Earth from space. We thus require sensitive measurement across the entire energy spectrum, using large telescopes with efficient instrumentation located on superb sites. Technological advances and engineering constraints are nearing the point where we are recording as many photons arriving at a site as is possible. Major advances in the future will come from improving the quality of the site. The ultimate site is, of course, beyond the Earth’s atmosphere, such as on the Moon, but economic limitations prevent our exploiting this avenue to the degree that the scientific community desires. Here we describe an alternative, which offers many of the advantages of space for a fraction of the cost: the Antarctic Plateau.
Glaciers and ice caps around the world are changing quickly, with surge-type behaviour superimposed upon climatic forcing. Here, we study Iceland's second largest ice cap, Langjökull, which has both surge- and non-surge-type outlets. By differencing elevation change with surface mass balance, we estimate the contribution of ice dynamics to elevation change. We use DEMs, in situ stake measurements, regional reanalyses and a mass-balance model to calculate the vertical ice velocity. Thus, we not only compare the geodetic, modelled and glaciological mass balances, but also map spatial variations in glacier dynamics. Maps of emergence and submergence velocity successfully highlight the 1998 surge and subsequent quiescence of one of Langjökull's outlets by visualizing both source and sink areas. In addition to observing the extent of traditional surge behaviour (i.e. mass transfer from the accumulation area to the ablation area followed by recharge of the source area), we see peripheral areas where the surge impinged upon an adjacent ridge and subsequently retreated. While mass balances are largely in good agreement, discrepancies between modelled and geodetic mass balance may be explained by inaccurate estimates of precipitation, saturated adiabatic lapse rate or degree-day factors. Nevertheless, the study was ultimately able to investigate dynamic surge behaviour in the absence of in situ measurements during the surge.
The ALFA mission is designed to map the entire sky at frequencies between approximately 0.3 and 30 MHz with angular resolution limited by interstellar and interplanetary scattering. Most of this region of the spectrum is inaccessible from the ground because of absorption and refraction by the Earth’s ionosphere. A wide range of astrophysical questions concerning solar system, galactic, and extragalactic objects could be answered with high resolution images at low frequencies, where absorption effects and coherent emission processes become important and the synchrotron lifetimes of electrons are comparable to the age of the universe.
We present observations of the old nova HZ Pup (Nova Pup 1963 No. 1) showing it to be an intermediate polar with an exceptionally rich selection of photometric periodicities arising from spin and orbital variations and beating between these two.
The number of cell types required for the construction of a metazoan body plan can serve as an index of morphological (or anatomical) complexity; living metazoans range from four (placozoans) to over 200 (hominids) somatic cell types. A plot of the times of origin of body plans against their cell type numbers suggests that the upper bound of complexity has increased more or less steadily from the earliest metazoans until today, at an average rate of about one cell type per 3 m.y. (when nerve cell types are lumped). Computer models in which increase or decrease in cell type number was random were used to investigate the behavior of the upper bound of cell type number in evolving clades. The models are Markovian; variance in cell type number increases linearly through time. Scaled to the fossil record of the upper bound of cell type numbers, the models suggest that early rates of increase in maximum complexity were relatively high. The models and the data are mutually consistent and suggest that the Metazoa originated near 600 Ma, that the metazoan “explosion” near the Precambrian/Cambrian transition was not associated with any important increase in complexity of body plans, and that important decreases in the upper bound of complexity are unlikely to have occurred.
It is both convenient and realistic to regard the solar radio-emission as being composed of a quiet permanent part coming from the whole of the sun's surface, together with a superimposed variable part emitted from centres of activity. The variable part can be further subdivided into various components to which separate reference will be made. The components are almost independent and add to one another to give the solar emission recorded by radio telescopes. For our understanding of the phenomena it would be a great advantage if the components could be completely and reliably segregated but this is not always possible. The results from a wide network of observational stations are recorded in the Quarterly Bulletin of Solar Activity, from which the intensities and characteristics of most of the components may be extracted.
This paper reviews our understanding of (a) the earth's ionosphere, and (b) the solar atmosphere, in relation to the recent observations of solar XUV.
The expected ionospheric characteristics are derived as directly as possible from the XUV observations and then compared with the well known E and F layer formation. Agreement does not come very naturally. There are indications of a high ionospheric recombination coefficient decreasing rather rapidly with height. It is found that radiations from the high ions have greater solar cycle variations than radiations from the low ions. This leads to some difficulty in explaining the constancy of the E to F critical frequency ratios. Both UV and X-rays appear to contribute to the E layer.
There are about 250 identified XUV solar emission lines from about 50 ions. The flux measurements for each line gives information on the number of corresponding ions in the solar atmosphere. Each radiation comes from a region with a well specified temperature selected from the whole available range 20000° to 2000000°K. This makes it possible to derive, (a) the amount of solar material in each temperature range, (b) the chemical abundances, and (c) the physical differences between normal solar atmosphere, centres of activity, and flares. The analysis is held up at the present moment until the problem of the dielectronic recombination coefficient is cleared. In due course a good distribution of matter with temperature should be available but the fitting of such results to chromospheric and coronal models provides many problems.